You will most likely get some bumps and bruises when learning the worm. Choose a large carpeted room without much furniture, a dance studio with soft mats, or a flat yard with soft grass that's free of rocks as your practice space. If you get some bad bruises from the first few practices, take some time off to let them heal before you start trying again. Choose a friend or family member to video you doing the worm, so you can watch it and see how you're doing. Look for parts that appear wrong and focus on fixing those areas in your sequence of moves. If you don't want the video shared publicly, be sure to remind them not to post it on the Internet. Try practicing the worm at a social event once you feel comfortable doing so. Your friends will probably be impressed that you taught yourself such a great trick, and may give you some pointers on improving or teach you other moves that you can do together.

Summary:
Practice in an open area on soft ground. Ask someone to take a video of you to help yourself improve. Show off your skills at a party or break dancing circle.