[noname219]

The trick behind the game is to lay down consecutive numbers side by side. I found that the most natural pattern for me is to put the highest number in the bottom right corner and to build up from there (in a snake pattern). At the end of the game, you should see a board like this :

0-0-0-0
0-0-2-4
64-32-16-8
128-256-512-1024

A pattern could give better results with human intervention at some strategic points : when the bottom line is filled with consecutive numbers, you could switch (mirror) the pattern so it could build up from the left, once there's a corresponding number, hit down, repeat.
Hitting "down-right-down-right-… left-right if stuck" creates a rainbow pattern every time but due to the lack of space, you get a game over quickly.

edit : lol : http://jennypeng.me/2048/