--Make sure you have privacy. Being relaxed is very important and few things can tense you up more the fear of one of someone walking in.
--Find something that will help put you in the mood. Many consider the brain the largest sex organ in the body. You can feed it with sexy thoughts about someone you're attracted to. If you like music, you might enjoy playing something that puts you in the mood.
--When touching yourself, don't just concentrate on the area between your legs. There are many other areas of your body that might bring you pleasure too.
--Experiment with various techniques. Some women like external genital touching, some like penetration and some like both. Some also like using toys such as vibrators. There is no "wrong" or "right" way to masturbate. It might take a while to find what you like.

Finally, try not to put too much pressure on yourself. You might not "get it" the first few times you try, but most people are quite happy that they persisted once they have gotten the hang of it.