Okay, I've played a few games, at seems like fighting the New Republic is almost impossible. They field such HUGE fleets, dish out MASSIVE damage, and are tough to destroy. Seems like the best I can do is drive away their fleet temporarily, with significant losses, only to have them come back with just as much firepower as before while I'm still rebuilding. Most recently, playing Empire of the Hand, I had a two-to-one planet advantage (still developing them, though) and the NR was still sending absolutely insane fleets against me. Watching my just-built offensive fleet (once I built up some more ships for it) evaporate guarding a planet convinced me I was in an untenable situation. And I set the difficulty at Beginner to boot.
What am I doing wrong?