if i'm at an AMP for the first time, MMS takes the house fee, then i'll lay out ~160 on the table. after that one of two things happens. either the girl wants to negotiate, in which case that's my bank to negotiate with, or she just delivers the service i expect, in which case it's hers to keep. i have never had anyone deliver limited services but expect the whole stack, fwiw. i think laying out some coin in plain view does help to validate that i'm experienced and ok to provide full services to, if they are on the menu at that spot. if i'm very happy at the end i may add another 20 as an extra tip.