I would not visit a parlour for my first time, I have visited one only once (Victoria House in Lutterworth), and I found it a bit clinical for my liking.
I lost my virginity in an upmarket whorehose in Amsterdam (the Yap Yum Club, IIRC). It was a memorable experience - it would have been more memorable if I hadn't had to get thoroughly intoxicated to overcome my nervousness. My boss paid, btw ...
I would not go for a girl your age - you might find the pressure of 'measuring up' (in both senses of the phrase) a bit too much, especially if she's a stunner.
Me? I'd go for an older lady with a 'kind' profile. Me? I'd let her know in advance of your adventure and establish a bit of a dialogue (not too much though - it can be seen as time-wasting) so that she knows what's what and gives you an idea of what to expect. Maybe (depending on your finances) if she offers 'direct chat' via AW you could talk to her that way, and she'd know you are not a TW.
I have enjoyed many excellent experience with independent escorts and only one or two disappointing ones - I think the secret to success is research: find a lady you like the look of, read her profile and see if something clicks with you, read her reviews, make contact. Don't rush - and expect to enjoy the experience. If you do come in the first minute (and I imagine many of us have!) then if you've established a dialogue (or at let let her know of your situation) I'm sure you'll come again
Me? I'm looking to end a longgggg period of chastity, but at 60 and being a very fat bloke I myself am having to screw up my own courage.
Good Luck!