In my current game, I've focused on economy (+20 with Federalists, and +50 or so with the chosen abilities). This allows me to keep my spending rate at 100%, and still have 300bc a month left over. I usually spend that on buying techs, which I can buy for around 2000bc each.
Still, the Drengin are owning everyone. They've got 1080 military strength (they have four or so stacks of five fleets each with four ships each hanging around their main worlds), while mine is only 104. It's nuts, and I have no idea how it happened.