It all depends on the place you go to and the girl you see.
If it's a known semi-legit, they will almost always confirm that you want a HE the first time they see you. Once they know you, it's automatic.
If it's unknown that looks borderline legit, you may need to ask or point and hope for the best. Sometimes you just have to go a few times until the girl knows you.
If it's a know holistic/body rub/FS place, the girl will will usually ask you want you are looking for (their menu). The worse the massage is and the prettier the girls are, expect to pay more.
Also, there's nothing wrong with a little negotiation if you think the price is too high.
You just have to start going and getting a feel for what you need to do at which place, sometimes you will pay too much and other times you get a great deal.
Just don't be cheap.
Typical guidelines for me are:
$40 - HE (some are fine with $20-$30)
$40-$60 Topless
$60-$80 Nude/BS/NR (there's a lot to be had in this range)
$80-$120 Many places this is FS
The sky is the limit at the premium spa and but since I don't opt for FS, other will need to give you more detail for this.