Coupla things: Tips. The word should be restricted to describing entirely voluntary recognition by the customer of exceptional service—except in under-waged occupations like food service, taxi driving etc. where it's pretty much the payment, but is still voluntary. If, as in an MP, there's a schedule of fees for upgraded services, and there's a negotiation between client and provider as to what you get for how much, then these are prices and not tips. The poor novice has enough to absorb w/o the hairsplitting that qualifies a tip that's a tip and distinguishes it from a tip that isn't a tip in some of these posts. They're fees for upgraded services, and if somone wants to tip beyond them, well, let's all wish we were so generous.
Standard: A half hour's intimacy at an SC, in an MP or at a minor incall will set you back $100-$150, and she'd prefer to be making that for her time too. So the lower upgrades or no upgrade gets you something like a dancer's reaction if you stop after a song or two—hardly enthusiastic. You'd best have finesse if you don't have funds. After the door fee, which buys you just the admittance and only minimal attentiion from the MPA (who gets little or none of it) the commonest half-hour pricing I've encountered is $20 for Topless, $40 Nude $60 NR, and $80 BS usually arranged and collected by the MPA (so the house can claim ignorance of what happens in the room) but sometimes collected at the desk.
How it works/what you're to do: As the customer, if you're polite and good-natured, you get anything she's willing and you can pay for. Neither will you be struck by lightning, nor will she demand you never darken her door again if you "get something wrong", The whole thing is a bout two humans interacting pleasureably; asking and talking makes it work better for every one. And you know something, it may be a first for you, but she's seen a lotta firsts, she'll make it work.
Oh, BTW. The in-room shower—especially if it's clean and the taps don't fall off—is definitely a sign of a place aspiring to high standards, You'll likely do fine there. But lots of places have only the one shower necessitating a towel-wrapped hall jaunt. How well the MPAs manage traffic generally accords w/ their management of your session. And some places have showers you'd rather they'd kept to themselves until the crud covered them; almost always best to take the same approach to the spa itself, even if at the cost of the door fee. Nothing wrong with asking to look around before deciding if you'll stay, y'know. You are the customer.