Can you provide any details? A quick once-over of a typical game?
You've described the game setup, but nothing about how you are currently going about your game.
One thing I try is:
0) Build Construction bases in orbit of your home planet(s). A very quick & easy way to double your spaceyard production in the first 2-4 turns.
1) Build basic missile ships
2) research ship capture
3) spread lots of capture escorts among the basic missile ships
4) research into racial techs or a higher-level weapons tech.
5) steal everthing I can get my hands on: LC's Engines, colonization tech, some cheapo weapons, and some racial techs if lucky.
The boarding parties can keep your military research pumping, while you concentrate on getting infrastructure.
(Using boarding parties to steal Allegiance Subverter tech is fun
)
IMO the best infrastructure tech to get is monoliths. Dosen't take too long, and gives you a very nice +100% to resource production.
Since you're an SE3'er, you should be well aware of the critical nature of chokepoints.
What you may not be clued into is the fact that storms and/or asteroid systems are a very effective barrier to ship travel.
Since supplies are based on movement used, not time, traveling through two empty systems can deplete the supplies of a warfleet, forcing them to turn back or turn into a suicide mission.
Also, simulate lots of combats, and do your math
to find out which components are better.