i think a good stragety would be to start out with only a few planets, create a large ground a space force for undefeat able defenses then have a large fleet ready and waiting for when your ready to quickley strike enemy bases one planet at a time. when your offencive army is destroyed repeat the process with the planets you've conquered
"Do what must be done, do not hasitate, show no mercy!" ~ Darth Sidious
"Peace is a lie, there is only passion.
Through passion I gain strength.
Through strength I gain power.
Through power I gain victory.
Through victory, my chains are broken.
The Force shall free me." ~ Sith Code