Best way not to get busted?

I realize you should never discuss $ in exchange for services and i'd never want to be busted in a sting so whats the best way to borach the topic? I typically ask the girl if i can touch (or ask her to touch me) so i know shes not a cop then disucuss what the donation would be. But not all girls are open to that. I sometimes have adrink or two before inviting the girl back so my judgement may not be the best. I don't want to sound paranoid, but having a criminal record would ruin me and especially one that involves soliciation. Hopefully some of you pros can provide better advice.