How do you finger yourself? Girls only?

I've masturbated before and I love doing it. I mostly play with my clit because I'm afraid to stick anything up my vagina in fear of infection. I think my hyme may already be broken because I use tampons during my period.

So I was wondering, how do you do it? How can I stay clear of infection? What finger should I use? How far is too far? What does it feel like?

Thanks in advanced!