Feedback is bollocks, 95% of girls will see punters with zero feedback -------------- they want the cash.
+1 I think lack of feedback is maybe what the girls are using if on reading the message something doesn't sound right and that is the clincher.
Just literally say in the message to the girl.
"Hi, I seen your profile today you look nice, are you available for a one hour booking at around 1pm on Monday. If so where about's generally in (whatever city she has put down on AW) are you based so I know if I can get to you ok or not".
That is all that is needed for a booking. Maybe mention to her very in passing that you are new to this if she replies to the above in a subsequent message. But really I would just mention it at the start of the booking itself personally if you felt the need (but saying that I know reading a topic today on UKE girls have said they would rather know these things in advance).
The problem I think punters might be doing when new to this is - which I also did too when starting out. Is start putting in their emails to the girls stuff like
"Hi I am new to this and I am nervous. I am considering punting because.....(then waffle about why you are starting punting). And then its... how do I go about booking you what do I need to do."
The girl will just read this and think 'I haven't got time for this' and just ignore you and cite lack of feedback as a reason if you ever challenge it.