a great way for beginners is to use the circle of 5ths.

The circle of 5ths are all the 12 keys organised in a circle of 5th intervals. The way to use it is to choose a key, then the 5 chords next to it are the basic chords of the key.

For instance in the key of F, the basic chords are: F, Bb, C, Dm, Gm, and Am.

Here's the circle http://library.thinkquest.org/15413/media/images/circleof5ths.gif

Red ones are minor keys, and blue ones are major keys.

Doc-Z