Have you thought about DMing a game of Dungeons & Dragons or of Paizo publishing Pathfinder Roleplaying Game? What has kept you from trying it? Did you like a Basic Box for either game? Book costs? Cold feat? Being overwhelmed by the thought of running a successful adventure or coming up with a campaign everyone would like?
I go into 5-6 things for both systems that if you learn, will help you to be on your way to running a fun and memorable session or campaign. I try and focus things down to help a beginner overcome the jitters or overwhelming feelings that can come with learning to be a new Dungeon/Game Master.