Things You'll Need
Instructions
Learn about your players. Different gamers have different desires when they sit down at the table. Some want to tell stories about their characters, some want to figure out puzzles and traps, and some simply want to fight monsters. By knowing your players' tastes, you will be able to craft stories and encounters that appeal to each of them for a majority of the time.
Steal shamelessly. It is a favorite saying of writers that there are no original ideas, and once you embrace this, you have a world of inspiration to draw on. If there is a favorite book or movie you'd like to emulate, feel free to use the basics of the plot, with the names and situations tweaked slightly. A fantasy game based on your favorite sci-fi movie might sound strange, but it's done all the time.
Prepare for the unexpected. Although a writer of a novel or film doesn't have to worry about things he knows he isn't going to write about, a game master never knows when his players are going to do something unexpected. If players ignore your carefully placed bait for an adventure, have a small side quest prepared at all times, something that can be placed at any point in the plot, so you have an alternative adventure for your players to participate in. A mission related to a character's background is a good choice. In addition, have a list of names prepared, in case your players talk to someone you weren't expecting them to. There are few things that break the illusion of a carefully crafted world than an unexpectedly mundane name; if you need the name of a non-player character, simply select one from the list.
Describe things just enough. Too-simple descriptions of environments and people can fail to capture your players' interest, and too much description can hamper a player's imagination. Paint a broad stroke of the scene with a few key details, and leave the rest to the players; the scene will have more personal impact for them, and you will get the credit. Likewise, a single distinguishing feature or unique quirk is more effective in describing a character than a drawn-out description of the character's wardrobe and demeanor.
Let your descriptions imply meaning, rather than simply tell it. When describing something to the players, don't simply tell them what something means, give them enough details so that the meaning is clear. Don't say the queen is overprotective of her son when you can say she gently slaps his hand every time he touches the ceremonial dagger on his belt.
Take advantage of technology. Whether you use online databases for rules or to search for images to use as props, the proliferation of smartphones, tablet computers and laptops gives you a tremendous resource as game master. Some games are entirely online, using webcams, voice software and mapping tools to connect players around the world.
Know the rules, and know when to ignore them. Few things can drag down an exciting game more than spending 20 minutes looking for a specific rule in a book or online and figuring out how it applies. A game master should know off the top of his head a majority of the rules for the game and be willing to ignore them when they might drag down the pace.
Enjoy yourself. Remember that a role-playing game is just that: a game. It's a hobby, and it shouldn't feel like work. No matter what happens, you are taking four to five hours to sit around a table with friends, and that should be fun.