Start here if you have never picked up a tile. These guides walk through setting up the table, dealing, the flow of a hand, what each suit and honour tile means, and the vocabulary you will hear other players use. They also cover the mistakes new players make most often, so your first game is spent playing rather than looking things up.
The order most people follow is tiles first, then set-up and seating, then a full hand from deal to win, then scoring. A glossary covers chow, pung and kong, and a printable cheat sheet keeps the basics beside the table. There is a guide to teaching someone else in a single sitting, an honest answer to how long a game actually takes, and a comparison of Chinese and Western rules for when you are deciding which version to learn.