You enter an MP. Pay the door fee. Take the obligatory shower.
Lay on the table and await your technician.  
Sometimes you are asked the question if you've been there before.
At ths point, you can either lie and say yes or tell the truth and say no.
Many times, they will ask who you saw if you say you've been there before. Now you need to lie and make up a name...and lie convicingly.

If you'd like to get a good idea of the place and you might even get to check out the talent before hand, ask to use the bathroom and kind of hop like you need to go bad. Most times, you'll avoid the screening questions and they'll let you in to use the bathroom first and then ask you the questions.
A lot of times, the bathroom is next to the staging area where all the girls are sitting or laying around. You can poke your head in, say hello and see the talent.
But if you get lost going to the bathroom, you'll gtive away that you've never been there before.
Or you can say, it's been a very long time since you were last there.    

I don't think there's any standard approach but I know that from what my friends have told me who patronize AMP's on a regular basis, but the first item you need to clear up is that you aren't LE. So you do need to touch her in a very provacative area.
She will ask what you're looking for.
Some guys are just looking for an HJ or a BJ, all the way up to FS and everything in between.
To make it easy, if you're looking for FS, you just reply: "everything"
At this point, most times, the girl will leave to retrieve a condom and lube herself up.

Once you become an established or regular client, the song and the dance is of course,
not necessary.

RH