I dont remenber quite the combos i used, but the best traits i believe where: subterrenean and creative (although it depends on the strategy you re using, as a warmonger you dont real need this and can spend the 6 points on something else, like +2 productivity of workers). +100 growth population was good to and i used that silicoid trait a lot, but you will see that the points can make a better combo. Other power trait is Unification, this goverment + subterrenean + +2 production + 50%-100% growth will make your civ/faction/house (what was the name in the game....) a killer monster.
Other good traits are spying -3 means +3 points for use in the traits above, in penalty of a bad spying,once you develop the syping techs, this wont even matter.
I dislike repulsive a lot, though many warmongers use it, because they just wanna kill, why bother talking, i tend to find diplomacy essential on impossible especially on hotseat/multiplayer games.
Bottomline if you are creative, you probably should be repulsive to, because you wont be doing much diplomacy, if you arent creative you shoulnt be repulsive, unless you spy a lot with efficiency or have a killer warmonger combo allowing you to have that 1 or 2 techs you really need,
Go always for automated factories and population growth on earlly start, also research labs are a must, micromanage your colonies every turn, for defense a couple missile bases are good to hold you till you have decent laser weapons like plasma, build medium or small size chips and just put plasmas on it, as you progress on research the space required for a plasma will diminush and you can have a gazillion small ships with a lot of firepower on it, sure your enemy will have prob a few titans, but what does it matter, your swarm will overrun just about anything on the map. Its kind like upgrading vet warriors on civ.
There are earlier weapons also very good, gyro destabilzor was a personal favorite, although on earlier basis i tend to use missile ships a lot.
Im forgeting other good traits, maybe i should install the game again, was a bit years ago, but the graphics turn me down a bit in nowadays, although for the time, they where pretty good.
I remember the existence of a huge page FAQ on the best and different strategies on this game, it was pretty well made.