In the situation where you cannot provide a reference you need to be nice and polite. Don't go asking a load of questions that are already on her profile. That can really piss off the ladies. Also you can pm some of the other lads here to ask about ladies they have visited. They may or may not reply but if they don't what have you lost.... nothing.
Also got to remember that at the moment alot of ladies dont ask for referrals so plenty of time before if and when that situation may arise on a more widespread basis.