Eight Useful Things to Remember About Gamemastering
1. You can't learn everything at once.
2. Understand the rules and talk them over with the players. If they ask you to describe something, do. Let them worry about whether or not what you describe is important.
3. Expect to extend the rules. No set of rules can be as ingenious as players. Use your common sense to handle problems that arise, and keep playing. Don't waste too much time looking up minor rules. Reserve the right to change your mind about rules judgements. ("This is my ruling tonight, but after I've thought about it, I may want to change my mind.")
4. Expect to be wrong sometimes. Admit it. Say "Oops," do an instant replay on the action if necessary, and get on with the game. Don't be a pushover, though. Sometimes somebody has to make an arbitrary judgement, and that person is you.
5. Be fair. Earn your players' trust. Players cheerfully ignore rules mistakes and hesitations, as long as they believe the gamemaster is not picking on them or playing favorites.
6. Be impartial. When you are pretending to be the villains and bad guys in your adventures, be as clever and resourceful (or bumbling and incompetent) as they would be. But when it comes to judging conflicts between the player characters and your non-player characters, as gamemaster you must be partial to neither side.
7. Be prepared. At first, use published adventures like "Rebel Breakout." Study them carefully. Think about how to present the characters and events they contain, and how to anticipate the reactions of your players. Later, when you design your own adventures, organize your thoughts and adventure materials before your players arrive.
8. Be entertaining. Ham up your characters, try to get across the huge scope and sense of wonder that's a part of Star Wars, and make every moment as action-packed and suspense-filled as it can be.