We will strip you of your cultural distinctiveness and give you our own. You will be unified.
Resistance is futile

Was over at my at my brothers, and he was playing it so I got interested, and it's really funny! Defenitely a must buy! The game just feels very crisp, fresh and adequately polished.
I just thought I'd add my newbie advent-viewpoint and how I played in the only game I've played so far.
On all frontier planets I had repair, reantimatter and hangars. With that tactical slot upgrade you can get like 5 hangars and still afford a few repairs and antimatter rechargers. When you have upgraded fleet research and tactical research theese guys can kill stuff fast. The turrets doesn't really seem to do much even though if you feel you have enough repairs and *cough* enough antimatter (wich you never can have) you might want to build a gun or two.
I would avoid having a too wide frontier if possible since you can't really move your fleets around that fast. On comparison the Vastari's ability to build their own phase lanes really should give them much more reactive fleets than you will ever have. With adequate "infrastructure" they can react more quickly on distant fronts than I could. Their bypass shield things are also annoying.
Make sure to fleet up all your frontier worlds and max out defences there. Combined with stationary repair/antimatter/bombers you will really eat stuff up. Do not let anything get past the frontier worlds, even though you might want to consider the planets 1 step behind the frontier as 2nd frontier worlds also destined for full defence so you can retreat etc.
Balanced fleet is defenitely the way to go, even though I tend to go heavy on thoose bomber drones boats. Works better against the AI than a player I guess

I got one of thoose desert planets close to the AI's border and just smacked up, I think it was 8 of the propaganda boxes. I was pushing out something like 40+ culture/second. On my distand and secure homeworlds I didn't really build any heavy defences, just tons of thoose culture guns (tactical slot) and trade stations (logistic slot). If I got any odd numbers of slots, wich you usually do, I just smacked down anti-matter rechargers, repairs and hangars as per normal. This is so if the enemy bypasses your front somewhere your pursuing fleet will still have it's supply of anti-matter and repair.
If you survive the beginning, can hold your defences, you can eat the AI one world at a time. Your culture will take care of the rest and in addition I think that lowered alligeance will result in less cash/mineral income for the enemy, so thats a bonus to the eventual overthrow of goverment

To sum up. Fleet up all frontiers. Your bombers/fighters alone cant defend them, but together with an adequate fleet that benefits from your repair/antimatter stations, you'll be inpenetrable. Bring up culture. I'm not sure what's the best way to build it, but I prefer building it on frontiers, the culture will seep back into your empire eventually, the logistic slots on your homeworlds are prolly better served with trade stations.