Not terribly experienced, but: I think Vasari can survive for quite some time at tech 1 in military (for missile frigates - I don't build skirmishers at all). Get half way through the civ techs for economy upgrades (so at least level 4). Then get back to mil tech to level 4 (lots of good stuff, and AOE attacks from all those missile frigates you have lying around). Then onwards with the civ tech for dark armada.

It's only if, for whatever reason, your opponent is not hitting you that you can stay at military tech 1 all the way to armada, IMO.

Playing defensively works pretty well. Of course that means probing attacks, looking for weaknesses, but otherwise keep your head down, use the pirates or allies to hold off more aggressive enemies if you can, and defend. You win if you get to armada (or at least, you have a very good chance). Defensive turrets and repair platforms hugely and cheaply boost your defending fleets, which lets you keep your supply research at a minimum (which otherwise really hammers your economy), which in turn combines nicely with those civ techs you're getting. The moment you hit armada you can spend all your money on tech and defences, so life becomes a lot easier.

Against the AI I like the Evacuator as the first ship for its colonise (saves me buying a colony frigate), and the grav-bomb lets you kill enemy capships when they try to run. Against people I like, um, the battleship, whatever it's called. The nanite AOE attack is crazy good for taking down big enemy swarms in the mid game, especially with your own missile frigates to back it up, and the overpower ability lets it tank pirates nicely to get xp.

But if you're keen on vast carrier fleets, which I am fond of on occasion, the Marauder is great. You can dance your fleet out of enemy range while the fighters chew, chew, chew.