There's no proper way really. The way that feels good to YOU is the right way. Take some time for yourself and sit back and examine your vagina. Try touching it in different ways and not how it feels. Use a hand-mirror so you can see what you're doing. Don't worry about doing it wrong, just relax and think pleasant thoughts while you touch yourself.
There's interesting websites (not shady ones - don't worry) out there where people post their own techniques and other info. Check out the yahoo directory: link