Here’s an idea for you: Before masturbating, try pressing your knees together and clenching your butt upward in rocking movements. This helps to stimulate the flow of blood to the general area—after a few minutes you should notice a difference in your vaginal sensations.
Self-pleasure is often rushed or abrupt. In The Illustrated Guide to Extended Massive Orgasm, Steve and Vera Bodansky say most people fail to take the best possible pleasure from masturbation because they “do it to relieve themselves” rather than for pleasure.

How you prepare to masturbate is important. Some prefer to take advantage of the heat of the moment, or you might want to take a bath first, or perhaps dip into an erotic novel to get some ideas. Don’t dive straight in. By the time you undress you should feel pleasantly warm and stimulated. Experiment with what feels good, tease your nipples, run your hands over the whole pubic region.