Well, I started with Firered and Ruby. It doesn't really matter which one you start with, though, since they program all the games to assume you've never played Pokemon before. They walk you through everything you need to know at the beginning of the game.
I just started playing pokemon too. My friend who has been playing pokemon ever since the DS came out. She told me to purchase pokemon black. So far its fun, easy, and very entertaining and ive only had it for a few hours. Hope this helps