A lot of what you read in reviews is exaggerated, and I think sometimes when a client is reserved shyness is contagious.
Here is my advice for what made me comfortable as an indy SP, along with what others have already said:
-the client introduced himself properly with his name and age and maybe a bit more info about himself.. he filled my booking form or texted me with a real phone number. he already had a date and time in mind
-the client has a positive attitude, asks the right questions and says what he's looking for directly, he sends screening info
-if he is shy and reserved, he can say that during the booking process so that i'm ready for it
-if you want her to take the lead, let that be known.. sometimes guys just wait there without doing anything or saying anything, and that's uncomfortable for both parties
-if you need to break the ice, i recommend booking more than an hour with the SP so you guys can have a conversation maybe over a glass of wine before heading to the bedroom.
-book the same provider more than once. you will become more comfortable with her over time.
I'd prefer a client be shy and reserved than aggressive and cocky, personally.

It's not a character flaw to be introverted and some SP are more suitable for a connection like this.