Make a fleet of StarViper squadrons, and a ground force of purely assault squads. Capturing Kamino makes this cheaper. Then, create a black market on both Rebel and Empire planets. After creating a black market, buy the Buzz Droid upgrade and the Disrupter Rifle upgrade to make your forces all powerful. Then, fight your way to Dathomir no matter what the cost. Capture any planets in your way and build palaces on all of them. By doing this you will get more credits and a higher population limit. Once at Dathomir, make a Defiler and spread corruption on the planet. This will allow you gain something extra on the battlefield. Destroy the space station and any spaceships after you corrupt the planet, then send your "hired muscle" to destroy all resistance. Once you have Dathomir, start making Nightsisters and a space station to protect the planet. After making about ten to twenty Nightsisters (depending on how much population and money you have), send your space fleet to the planet closest to Dantooine, unless you already control them. With Dantooine, you can make Vonskors hunt Jedi and Sith. You should have capital ships and such by now. Make a few capital ships and destroy the Rebels if you created the Aggressor class, and the Empire if you created the Mandalorian Capital Gunship. With your capital fleet, most planets will fall to you with no casualties on your side if you just auto-resolve each battle. Destroy each space force and then destroy the ground forces with your Nightsisters and assault squads. Once you have destroyed all but the last planet's resistance, make Vonskors hunt down the Force users, because they will most likely all be on one planet for a last stand.
Always try to corrupt, enslave, build a black market, bribe, etc. any possible planets. This gives you sight on the planets base and units, in addition to many credits. This will also make the game much easier.
If you play as the Empire in Galactic Conquest or Multiplayer mode against the opponent with the Death Star (II), corrupt all their planets. In Multiplayer mode, look for the Death Star (II) on planets. Make sure you have the 38,000 credits to destroy it first, then sabotage it so the planets are still alive. When it is sabotaged, it cannot be constructed again.
In space battles as the Empire, put an Interdictor cruiser in the little box when organizing a fleet. By doing this you can send in your forces to a battle and stop enemy ships from escaping to hyperspace using only the Interdictor. When your opponent attacks the lone Interdictor, hyperspace in your reinforcements directly on top of them. Imperial Star Destroyers work best for this and provide a big surprise to an enemy player.
While playing as the Empire, get the Death Star and a Scout Squadron. Use the Scout Squadron on the opposing enemy's space station. First, bring it up on the map, then use the Star Destroyer's special weapon on it. Sometimes the enemy in Galactic Conquest mode will go to hyperspace.
While plying as the Empire and you want to destroy planets with the Death Star (II), use a Probe Droid to scout the planet. If there are is no space units, blow it up. Note: It is recommended that you blow up the planets with units or heroes on them.
When planets are destroyed by the Death Star (II), their ability (for example, T2-B tanks cost 20% less to build on all planets) will not work.