Starting Out
In the beginning levels of the game, the enemy will not attack your star base while other planets are under your control. With this in mind, you should always control at least one planet to keep the enemy from attacking you directly.
Expansion
Do not expand too far and try to control too many planets. Besides your star base, you should only control up to two additional planets, and these should concentrate on food production.
Taxing
If you need additional funds, raise the tax rate on one of your planets to 40 percent. This planet will produce credits, but its growth rate will drop to zero.
Platoons
Make sure that your platoons have 200 soldiers in them, and that all soldiers are fully trained and possess the best weapons and armor. While the cost is great, your platoons will be unstoppable.
Enemy Strategy
The enemy will usually try to take planets that will prove useful to them or you. The best defensive strategy is to have four platoons on every planet and four platoons and a troop transport in reserve.
Capturing Resources
Allow your enemy to take a planet that you have no interest in, then immediately take the planet using an attack force of four platoons. You will find that the enemy has left his own resources behind, which you can use for yourself.