I've found that a nice surgical strike can do wonders for the Rebels in space.
Build up one planet to have as many space and land production capability as possible, then bring Mon Mothma to that location to discout all of the costs.
If you encounter an Imperial held planet with a massive defense force like a level 4 or 5 space station, build up an attack force of 25 Y-wing squadrons. When they hyper in, focus on nothing but the station. That will take out the garrison units spawning in all the time. Retreat with whatever is left, then send in a "regular" fleet to mop up.
"Politicians campaign in poetry and govern in prose."
ThRaWn90,RAL_Thrawn,HPGR_Thrawn, Rogue 6
Born And Bred In XWA Country