It's been beaten to death here.  Besides, all you need to do is check her web site.  If it's an agency, don't bother.  In fact, the best gift you can give her is a return engagement.

That in order to bring lingerie is best to know the lady well.. Maybe ask her her size after the first encounter or even a gift card from any lingerie store. Some ladies as the previous poster stated, have a list of gifts on their site in case you would like to bring a little extra. For agency girls, I would say that the best gift is a tip being that they split the total (60 for agency, 40 for them). If its a duo, I would bring a nice bottle of champagne, wine or chocolate covered strawberries which is nice and can be enjoyed by all parties involved.

You have to get to know your Provider a bit before you start buying Gifts. My Provider loves Gifts. (well besides the Money). She loves White Chocolate Candy. During almost every Session that's what I buy her. Now remember when you buy a Provider Gifts, don't ever assume that there will be a Discounted Price on the Session. Just saying.

and then you can chat about her likes & dislikes.  Many gals state NO FLOWERS as it's not cool to have in the room if she has other appointments...  she likely going to trash them before going home.  

Be on time.  Be clean.  Have the correct donation ready.  Follow he donation instructions & do not make her ask for it. (This shows you read her ad / web site.)  Be dressed & ready to say good by pretty promptly when your time is up.  Leave promptly.    

Bringing excessive gifts might freak her out as it is not the norm.  With a fav, a VS or Fredrics gift card is nice...  she can order what she wants.  Very cool around the annual sale time.      

These things will make her happy to see you.

I've never met a gal who didn't like scented candles.

Jewelry is nice too like a pin or bracelet.

But remember it is not required.