As long as you have a valid major Credit Card, and the 2 month free trial code (which can be found in a lot of Xbox games, it is a card with a code), you are ready to go LIVE. You need a high speed internet connection, and an ethernet cable to make your Xbox go on-LIVE, which I suppose most people already have. A headset is a plus for the online gaming experience. If you think you want to give Xbox Live a try, I'm sure your local EB Games employees will give you tips to help you get on..
Also if you are thinking about going the full year, it would be pretty smart to get the Xbox Live Starter Kit, which should include a 12-month trial, the headset, and maybe some demos/bonuses. It cost up to $70 though, but just a heads up.