Totally agree with Smiths - I have specific services that are a minimum and need to confirm they are available.
I have never actually spoken to a WG on the phone about services. I almost invariably first make contact via AW e-mail, I write a very nice polite introduction to myself and why I want to see her, then tell her what I really enjoy - as Smiths said - don't make it explicit as in I wanna stick my tongue down your throat and then rim your arse!
I just put a list of the acronyms as per her likes list. A typical example would be e.g. "I enjoy a slow sensual GFE style seduction, DFK, OWO, RO, 69, rimming, various positions, finishing CIM".
Have never had any issue with the girl confirming everything I've asked for is ok, and delivering as requested.
Only exception to AW email is if I'm out on the road contacting a plan b - in this case I always contact via txt and send a first msg saying I've seen her profile on AW and ask about availability/times: if she's available I follow up with something like "Looking for 1hr GFE, DFK, OWO, RO, 69, rimming, various pos, CIM - is that all in standard rate?" Then assuming she replies in the affirmative I confirm the time.