Try to steal at the first sign the pitcher is going to the plate. If the pitcher is right-handed, watch his glove hand and shoulder. His shoulder will open toward first on pickoff moves and stay closed when he's going home. If the pitcher is left-handed, watch his feet.
Lefties tend to open their hips when going to first and close their hips when going home.
The best time to try to steal second base is when a left-handed batter is up because he blocks the catcher's view of the runner. When stealing second, glance back after three or four strides, or at the crack of the bat. Run loose, with no tension. Run in a straight line. Home is the hardest base to steal.