Don't double early in the game unless you have an overwhelming advantage.

A bad double:

http://brainking.com/en/ShowGame?g=1118690&i=4

Why not double early?

When you double, you surrender ownership of the doubling cube to your opponent. When you double, then only your opponent can double later. The ability to double is an important strategic advantage. You should not give up that advantage without a clear reason to do so. In money play, you should not double unless the odds are 2-1 in your favor. In match play, the doubling point varies depending upon the match score.