You can do this full-on, or face towards the side. The side shot can be quite sexy, highlighting the hips, a bit off the bum, the thighs, and part of the chest. Crawl slowly, and sensually. Crawling can be done on the floor or on the bed. Guys, this is not just for gals.
Crawling is sexy, period, no matter who is doing it.
And please, by all means, put a blanket or something soft on the floor. Or, you could unbutton a shirt all the way, just allowing part of the chest to be exposed. If you are a chick with long hair, let your hair flow down over your breasts, sort of hiding your nipples. It's a classic shot. Or you can simply stretch your arms up, piling your hair on top of your head, or run your fingers through your hair.