When I first contact a provider, it is via text. I say I am responding to their ad on (whatever site their ad was on) and that I am wondering if they have time and what is the rate to host a (time duration) (type, usually erotic) mutual nude and mutual touch massage at (whatever time I am looking for). I then say my ideal session would include release and a shower together at the end.
This has never failed me. They can either not respond(which means we probably were not a match and that I have saved myself from a disappointing session), say no to certain things(which means I know what I am getting and what they are comfortable with), or agree so they know what you are expecting. I have asked masseurs to various fetishes(watching them piss, watching them release, nipple pay, licking, and other sensual elements) if I felt like we had a connection on a second meeting and the worst they can do is say no.
While some on here like the thrill of not knowing what will happen and the anticipation of the "will he or won't he" get naked, I am not a fan of gambling money on that when I have expectations.