Try being a little more careful about where you go - you can look on the system map by hitting tab. Try to find pirate fleets that don't have 10 other pirate fleets around them. You could stay around the hegemony system defense fleets, at least for the first rush - it's pretty safe right next to them, and you can strike when you see an opportunity. If they wreck a bigger pirate fleet you could go after what's left and maybe find some easy pickings.
Other than that, though, the game is hard...