I can tell you a bit about getting the mid-level models/actresses/dancers/porno girls.
By mid-level I mean girls who are in a magazine or a show here and there but they're not full time professionals, and they're not famous. Well, they often try to pretend like they are!
These mid-level girls are not that hard to find in NY and LA. So for starters, make sure you're in a town that has these girls. Once you're there, you have to make sure you have a well-developed identity or game won't help you all that much. You have to be the guy these girls can picture themselves hooking up with. I know a ton of these girls. They hang out with rich guys sometimes, but if you're cooler they sell the rich dude out in a second. They make fun of those guys behind their backs. It's pretty funny.
If you have done well with social networking and your identity, you can meet these girls without teasing that much and they will respond. Of course you can't come off as needy, but there are situations where you will have so much social proof that models will be super nice to you and you can be nice back. Believe it or not, there are model/actress type girls who are really nice people. I was hanging in a place the other day where this model chick kept buying me drinks and offering me cab money just 'cause I was friends with her friends. These girls love certain kinds of guys - dirty musicians, bad ass guys, alpha types, cultured educated guys who know about cutting edge fashion/music/etc. "Scene-ster" type guys. Okay, so that's not really new information, right? But, I think a lot of people tend to disregard the effort that needs to go into becoming one of those guys. They'd rather just work on the routines and stuff. Your identity is an important part of your game.
As for some of the technical stuff:
If they are slightly famous, never admit you know who they are. For example, one of my students has gone on a few dates with a famous female newscaster. I told him to just kind of skip over the whole topic of her job, and that is working well. He's not advanced enough yet to get her in the sack quickly I don't think, but ignoring the element of fame will keep you on an equal level of social value, and keep you in the game so you can improve.
Treat her like any other girl. This is easier said than done. The hard part is projecting comfort. You must become accustomed to hanging out with super hot girls. Then you will always project comfort.
I know this may sound lame, but it helps to be in a job or community where these girls are plentiful. For example, lots of photographers bang models. As part of their job, they have to boss hot chicks around all day. This is a great start. I used to have a job where I was around actresses all the time. It was cool because they automatically accept you since you're in their world... but it also resulted in me being accepted by actress types I just met 'cause they could tell there was a reason I was so comfortable with them. The reason was that I was so used to them and most men are not.
David D. says make fun of the model thing, like "ooh cool, do you have really sexy toes? Are you like a toe model?" I like this. It's worked well for me.
Have specific knowledge of your target girls. For example, most ballet dancers are heavy smokers, they do coke, and they hang out with gay guys. They are bad-ass chicks who revel in the dichotomy of presenting a good girl ballerina image to the outside world, then they like to be really bad behind closed doors- do drugs, puke up their dinner, then get roughed up in the sack. Knowing stuff like that helps you relate to these girls in a way that is attractive. For me, I like ballet dancers more than models and actresses so I looked into it. I find actresses to be high maintenance and attention-needy. Models are too skinny for me and they have poor muscle tone sometimes from the eating disorders. But, to each his own. Let me repeat the most important point here: find out about your target girls!