Many people are introduced to poker through playing other games. According to the bios of the World Series players, such gateway games include backgammon, chess, and other card games like bridge. It is a nature progression in that all of those games include an element of luck and an element of skill. I offer one more game that is good practice for honing your poker skills--rochambeau, aka Rock Paper Scissors.
Why RPS? It is perfect in its simplicity. I hate the fact that people use Rock Paper Scissors to decide who rides shotgun or who will be the DD for the night. It reduces it to the equivalent of drawing straws. It's not. If you know your opponent, it has no element of luck at all. For my money, Rock Paper Scissors is the best exercise there is in reading you opponent.
To know when the player across from you is sitting on aces or has completed his flush, first know when he will throw scissor. Is he the type of man who would open with rock? Is he capable of following up two papers in a row with another paper? It sounds crazy, but the more you can read people in other games and in life in general, the more successful you will be in poker...and, actually, life in general.