General Rahm Kota is the first boss you will face as the Apprentice. He is faster, tougher and far more dangerous than any of the Militia or Stormtroopers you fought to get to him. He requires some strategy to beat and can be tricky if you're fighting him for the first time.
Hit him with a Lightsaber combo right off the bat. This will help you get a feel for how he works. You won't get too many hits in before he starts to block, but this will test his limits.
Use Force Push on him. General Kota leaves long intervals when he doesn't hit you. Use this time to charge up a big Force Push. When he drops, rush forward and hit him with a Lightsaber combo.
Throw things at him. You can't Grip General Kota for very long. Instead, use the debris around to slow him down. It won't do a significant amount of damage to him, but it will give him pause. When you can Grip him, hit him with a Cannonball (Grip + Force Push.)
Use the scenery as cover. When Kota projects a bubble, he is about to throw things at you. There are two large rubble piles near the front of the screen. Get behind these when Kota starts throwing objects at you.
Keep the pressure on. If you give Kota an inch of breathing space, he will hit back with a vengeance. Keeping him busy prevents him from pulling nasty tricks out to hit you with.
Stay off the floor. About halfway through the fight, the floor will begin to glow. When it does, jump up on something. Staying on the glowing hot floor will eat away at your health.
Blast him with the finishing moves. Every boss (and many larger enemies like AT-STs) have a set of finishing moves you can perform on them for extra points. These consist of a series of buttons which you need only press once, but must press quickly when they appear. Pulling this finish off will score some major points for you. Plus it looks sweet.