TLDR: Aion is a good starting point but Kali is better until you hit level 25, the buy short list; Light Machine Gun, Repair Drones, Nuclear Mine, Repair Autobeams, Energy Generator, Retaliator, Module Amper, Engine Rigger, and Adrenaline Shot.
Abilities, Officer Briefings, and some builds what to use and why. First the abilities, hopefully I can save you some money by not having to do the trial and error thing too much. I’m Just going to go over what I consider the best modules/officer briefings for the slots and why.
A quick look at your starting abilities on the Aion:
(P) Primary Weapon healing/damage beam: Keep this in mind the Aion heals a maximum of 800 and close range and does 600 damage at close range, so 75% of the time healing will serve your team better than dealing damage.
(S) Light Rocket Turrets, terrible, in the Aion unless you’re shooting at a Dread use your primary weapon by the time you get to Koschei you’ll have the Light Machine Guns switch as soon as possible.
(sI) Tesla Coil Pod, great damage output, but an even better distraction when people can either shoot at you or destroy the pod.
(sII) Repair Pod, good enough but better things come down the line. Use the pods as often as possible.
(sIII) Blast Pulse, one of the few modules I would almost, ALMOST call OP for Tacs.
(sIV) Autorepair, not bad, but energy > health for tacs.
(O/B ___) All O/Bs are 101, the 101 briefings will get you to 25 but you should upgrade as you go. I go over what upgrades are wanted a little later in the article.
Secondary Weapons: Light Machine Guns are generally the best / most useful option here. Good firepower combined with excellent range for a secondary weapon mean you can get kills on fleeing corvettes and low health destroyers fairly easily. Tesla Turrets deal AMAZING damage but you will need to be almost on top of the enemy to use it so I don’t normally use them.
(sI) Primary Modules: I would say 99% of the time Repair Drones will be what you want to run here. They will help you survive corvette runs, sniper attacks, and a bit extra healing when needed. Until you get it you should consider Beam Amplifier, just remember it drains all your energy so use it when you’re already out of energy or if you have an energy generator in slot IV. If you plan on using Energy Generator Beam the way it should be used is 1) drain energy, 2) Beam Amp, & 3) IMMEDIATELY after using beam amp hit Energy Generator and power to your weapons. You will not believe the healing output that combination gives you.
(sII) Secondary Modules: Repair pods will be your primary ability until you get the Nuclear Mine, then switch to it ASAP. The Nuclear Mine will make corvettes have a bad day, when they start their run on you with about 50% health they are going to have a BAD day! A recent test confirmed that a Valcour looses 80% health when hit by a Nuclear Mine deployed with power to weapons. It is my opinion that the Nuclear mind is the best option for Tac Cruiser players because it gives you both a defensive and offensive weapon. Placing the mine where you think a corvette will come through to attack you generally means they will be starting the attack about 50% health which generally means you should be able to solo kill it. As an offensive weapon you can launch it straight at a close enemy and move away, you may take damage but it will do significantly more to them. These lead to three fold deterrent to Corvette pilots damage, demoralization, and denial, damage is obvious. Demoralization because having to attack an enemy when you are starting at 50% health and not knowing why or even knowing you ran into a mine SUCKS. Because veteran players will see the Nuclear Mines they have to avoid them, which means they have to deviate from their planned route.
(sIII)Perimeter Modules: This depends if you are more concerned with your own survivability or being able to put out MAXIMUM healing. For survivability Blast Pulse is the only way to go, if you want max healing go with Repair Autobeams. Eventually you should get Overclock pulse for team support, it’s amazing when combined with Overclock Module(sIV). Healing focus is easy, Repair Autobeams make it easier to heal because the beams will focus on up to two targets within 1200m of your ship. Blast pulse combined with Nuclear Mine generally means corvettes aren’t a problem, unless it’s a heavy corvette but even then you have a fighting chance. If you manage to get a well coordinated team having a healer with Overclock Pulse can make the a significant difference to the team, but it really should to be used with a team using long cooldown modules.
(sIV)Internal Modules: Honestly this is the hardest section to pick an ability from. Energy Generator is IMHO the BEST if you want to dedicate yourself to healing. With descent energy management you will (or should) never have 0 energy unless your using Beam Amp. A close second place for sIV is Target Warp, this combined with Slow and Steady can give you amazing survivability without sacrificing mobility. I use a Target Warp equipped Koschei when there are a lot of enemy corvettes on the field. It also means when your dreadnoughts warp into the enemy team you can jump slightly after and keep them up. Overclock Module(OM) should only be considered late game if combined with Overclock Pulse(OP). Use OP and then OM then OP which speeds up OMs cooldown.
Communications Officer: Retaliator is your goal here, but level 46 is a long ways away. Until then Desperate Measures is as good as it gets for Tactical Cruiser although Communications 101 is fairly good too so if you dont have the money keep 101 until level 46 where you unlock Retaliatior.
Weapons Officer: Weapons 101 will get you by, but upgrade to Module Amper(MA) when you can. Upgrading to MA means when you activate a mine, pulse, or Repair Autobeams or drones they will be 30% better. Glass Cannon can be considered, just remember you ARE a TARGET and more than likely when you need that 25% damage you will be under 100% health, think corvette runs.
Navigation Officer: Navigation 101 works until you can get Engine Rigger for the speed. This turns the Koschei into a ship that can keep up with the fleet, which in turn means better team performance and a higher score for you. If you’re using (sIV) Target Warp then using Slow and Steady can be a huge boon, just remember you will need to use warp and generally not power to engines to get out or into healing positions. NEVER EVER use Navigation Expert, you will have 30% less time powering weapons or shields, it SUCKS on these two Tac Cruisers!
Chief Engineering: Use 101 until you gain access to Adrenaline Shot, then nothing else should be used. There are no options for healers, don’t even think about it. Honestly there's nothing in the engineering officer briefings that is even close to the value of Adrenaline Shot. The most ridiculous thing is healing someone else while taking damage and being healed, it is almost impossible to run out of energy in that situation. Another bonus is that it is very good on any heavy ship or on that takes a lot of damage just for the energy gain.
Base Tactical Cruiser Shopping List:
Level - Iteml - Misc
01 - Aion - Don’t buy if you have the Kali
04 - Energy Generator
06 - Repair Autobeams
06 - Slow and Steady
10 - Target Warp
11 - Adrenaline Shot
12 - Light Machine Guns
13 - Desperate Measures
18 - Module Amper
20 - Repair Drones
25 - Koschei
27 - Nuclear Mine
34 - Engine Rigger
46 - Retaliator
Once you have these abilities think about expanding on the base Tactical Cruiser abilities. If you enjoyed the video swing by my stream I am generally live Monday-Friday from Noon Pacific to about 6pm.
Knowing the terrain is important for every class, but as many things are for Tac Cruisers, it goes double for you. You must know firing lines and paths of escape. Where players are going to break line of sight(LOS) and where you can break LOS with the enemy. Rings of Saturn is one of my personal favorite maps because it has so many places for healers to snuggle up in and be quite safe for a time. Kappa base is probably the second best and Dry Dock is not far behind. All maps have great spots where you can turtle up and heal your team for the entire duration of the match timer. They also have plenty of place to dart from cover to cover with either power to engines or warp jump. Learn the maps, learn them well, use this knowledge to help position your team in an advantageous position to DESTROY the enemy healer that knows the terrain too. 
It can not be stressed enough, keep your head on a swivel! If you have the Kali don’t even bother getting the Aion, you can play Kali until you hit lvl 25 and the other hero ships as you see fit for a break, banking all that cash to outfit a Koschei completely as soon as you hit level 25. If you don’t want the $40 pack or can’t afford it, worry not the Aion will get you to 25 almost as fast. Just make sure you don’t blow your money on useless abilities / OB like the Artillery Pod. Healing can be very rewarding or completely underwhelming. The more healers you have on your team the worse each of your score will be. If you only have an Aion and some one on your team brings a Koschei change ships, your not going to score well the best you can hope for is healing the Koschei up from time to time and getting a few repairs in here and there when the Koschei isn’t paying attention. My next pet peev is Double Koschei when your team has no DPS on the field, switch to the Trader Zmey or if you have it the Huscarl to up your teams DPS. Remember if your team can’t kill the enemy ships there is no point in healing, back to all of you playing Aions when there is a Koschei on the field you will get a better score playing a Trader Zmey than you will in that fully kitted out Aion. (unless you’re full on level 34 combat Aion) And finally, don’t lock yourself into playing only healer! Play every class at least until you understand their basic mechanics. If you have the Hunter Pack play the Huscarl and the Silesia if you don’t just play the Trader ships, honestly they are decent for what they are, the Mercenary ships just give a little better idea of high tier game play.
Aion #1 This is an early game Aion build, you should be able to have all the pieces in a few hours of playing. Generally with this build you should use all of your energy then hit the beam Amplifier when you need to heal as much as possible with your primary weapon. Repair pods should be dropped every 30 seconds (or as they are ready) to keep a field of healing available for you and your team. Try and stay around 1200m away from friendlies so you can use Repair autobeams if things get rough. Energy generator means you can Beam Amp and then Energy generator, then power to weapons so you get the Beam Amps extra power to healing plus the energy to weapons healing power, it's AMAZING. The 101 officer briefings are used so you can have the money to spend on the needed ship abilities and the ship itself. 
Aion #2 (Combat[ish]) So this is one of the screw around builds I use once in awhile it is a mid to late game build, I find it generates a little bit better score than the Cattaro mostly because you can heal and fight. I use Tesla Turrets because you can burn close up enemies down quickly. Tesla coil pods are what you should use if you find you can survive long enough to get away from enemies, if you find your having a hard time switch to Repair Drones Nuclear Min is an amazing offensive weapon when launched into a group of enemies immediately followed by Blast Pulse, then get out of dodge! Target warp should be used to jump away from your enemy or to a corvette near the enemy. If you decide to use Engine Rigger down the road you could switch to Overclock Module to have insanely high burst damage. Desperate Measures is nice and can give you an extra blast pulse and mine, but should be upgraded to Retaliator ASAP so you don't have to almost die to get that extra damage. Module Amper is 30% more damage to your TCP, Repair Drones, Nuclear Mine, & Blast Pulse. Engine Rigger can be used if you feel comfortable with your survivability conversely if you want more use Slow & Steady. For survivability use Engineering 101 once your comfortable with loosing some durability switch to Adrenaline Shot.
Koschei #1 This is my healing only focused Koschei build, it is amazing if you have good team support or almost no harassment. LMG because the range is much better than the Tesla Turrets for killing off the fleeing corvettes. Repair Drones mean I can survive any single corvette run 95% of the time, multi corvette runs require team support with or without this module. Nuclear Mine is better than anything else in this slot IMO for the reasons stated in the ‘sII’ section. Repair Autobeams mean you can look around and not drop healing friendlies. Energy Generator makes keeping people alive easy street. Retaliator means you should try and take damage once in awhile with your shields up so you can lower your cooldown timers, Desperate Measures or 101 can be used until you get Retaliator. Module Amper is my prefered choice because of the boost it gives to Repair Drones & Autobeams and the Nuclear Mine. Engine rigger makes keeping up with the team easier, until you get it run 101. Adrenaline Shot is a must!
Koschei #2 This is a much more survivable Koschei build than the previous one, I use it if playing solo or when there is a lot of harassment going on because it regularly kills corvettes. I use the Tesla Turrets because they rip new corvette players a new one, veteran players know to sit back a bit so they can’t be hit by them. Repair drones increase your survivability significantly. Nuclear Mine makes an excellent offensive and defensive weapon, and its fun getting kills after you have died. Blast pulse gives you an amazing corvette deterrent especially when combined with the Nuclear Mine. Target warp is how you keep up with your team, or get out of trouble. Desperate Measures will get you to Retaliator, then switch. Module Amper is needed because of the 30% increase in module damage. Slow & Steady makes you 10% more survivable, which is a good thing! Adrenaline shot is always needed for this ship.
(sI) Primary Modules: I would say 99% of the time Repair Drones will be what you want to run here. They will help you survive corvette runs, sniper attacks, and a bit extra healing when needed. Until you get it you should consider Beam Amplifier, just remember it drains all your energy so use it when you’re already out of energy or if you have an energy generator in slot IV. If you plan on using Energy Generator Beam the way it should be used is 1) drain energy, 2) Beam Amp, & 3) IMMEDIATELY after using beam amp hit Energy Generator and power to your weapons. You will not believe the healing output that combination gives you.
