Be sure not cast too far. If you are trying to get out further get a longer rod or jig pole.
Dont jerk back like the guys on TV. Crappie are called papaer mouths for a reason. a good example would be: if your rod is in a rod holder and you see the bobber move, the motion f picking your rod out of the holder should set the hook. A flip of the wrist should do it, you might be using a big hook or dull hooks!