We all know that 'digits' is very much a VMMV experience for pooners and SPs. Some don't allow it at all, some allow it sometimes, etc. (and then there's those of us who particularly enjoy it!) This isn't meant as a way to convince your favourite girl to give this to you if she doesn't already. If she'd rather not provide it, that's her right: her pussy, her rules! However, there are some good guidelines to follow if you see an SP that DOES provide it so that she will KEEP providing it to you.
1) Keep your hands clean! Scrub well around cuticles and under your nails when you shower at home or at the incall.
2) Make sure you trim (and file, if necessary!) your nails well before the visit. Check the edges of your nails, too; even a pussy that can take a pounding can be easily scratched with a sharp fingernail! That's going to kill the mood, believe me.
3) THIS IS THE MOST IMPORTANT RULE.
IF the lady enjoys anal/digit play, and you do too, DON'T DOUBLE DIP. SERIOUSLY. JUST DON'T DO IT. The bacteria in the anus and the bacteria in the vagina are not compatible! When the former is introduced to the latter, infections can result that can seriously affect a lady's ability to do business, among other things. If you cannot keep track of which fingers (or other things!) have been where, excuse yourself briefly and wash your hands before putting those fingers elsewhere! I cannot speak for the other SPs, but I can tell you that I would certainly rather THAT than a UTI!