I know there are many providers who enjoy receiving DATO.  What is the best way to let a provider know ahead of time so that she can be ready for it?

personally, i do my negotiation after verification prior to meeting and if you're into that, it's best if you tell me beforehand so I'm not surprised.  I'm personally always ready for it, seeing as i specialize in things like body worship.  

I know a lot of ladies don't do any pre-session negotiation; in those cases i'd imagine that you'd just ask he if she's into DATO. If she responds that she is, you should be good to go (hopefully).

good luck to you.