Before you go on and start doing the worm, you need to figure out just what the move is all about. Watch some videos of it and see Michael Jackson performing the move as well. The more you watch him, the more you will be able to associate with his technique, and the more likely you are to get motivated to perform it better.
When starting off, go ahead and lie down on the floor. You need have your belly facing downwards, and you should position yourself in a manner, which makes it look like you are about to start doing pushups.
Now go on and bring your toes over your rear end. You need to bring them back at a forty five degree angle, and you can perfect this by doing a lot of practice. You need to ensure that when you are moving your legs, the rest of your body stays still and in place.
Next you need to push your body up with your arms and pretend to start wiggling as you bring it back down to the floor. When your hands hit the floor again, go ahead and kick out with your toes once again. Just remember that when your toes are on the ground your arms are in the air and when your toes are in the air, your hands are in the air.
Now go on and repeat these moves till you are tired of doing the worm.