The Rebels can see every move you make, and can also with a small force, slip past any blockade you may have set up.
Never leave a planet unguarded in space or on land. However, build these last as the bigger your base is, the more turbolaser towers you get. If you can, also build a shield generator and/or turbolaser towers.
Try to keep every planet in your control well defended on space and land with at least one Victory Class Star Destroyer and a level 2 or 3 space station in space.
