Assuming you're new and building your portfolio, then money is the easy answer. You just have to stand your ground and stick to your guns if you're paying. Understand that YOU ARE THE BOSS. If the model shows up and wants to leave early, then let her leave. And then refuse to pay her, or prorate the payment for the time she actually was there. If she (or he) shows up and is lollygagging around and half-assing it, then send them home as soon as it's clear you're wasting your time. For glamour especially, the professional models don't care if you just bought your camera that day. You just have to use your spidey-sense and make judgement calls based on portfolio, word of mouth, and pre-shoot communication as to whether or not the model would be a good fit.
Hiring friends to share the cost is usually pointless IMHO. You'll get half a dozen guys to all shoot one model, they'll all shoot at once, the model won't know where to look, or will be rushed and there'll be no creative collaboration so far as where to pose, how, etc. There's a reason why these types of shoots are usually referred to as "gangbangs". It's generally not pleasant for anyone involved. One complaint I would hear a lot from photographers who did such things was that at the end of the day, everyone got the same shots, that is: model is on a nice chaise lounge, maybe with a decent lighting setup that someone went through the trouble of arranging....and then every photographer there took turns shooting over one anothers shoulders in a frenzy, and now that cool shot you think you got is very similar to 40-50 others that are now being posted online.
My advice is to try facebook groups, then instagram, and then modelmayhem again. Be upfront with what you are expecting in terms of theme/style, limits of nudity, usage of images, expectations for release forms, time/scheduling, etc. The more info you provide, the less surprises there are, and it'll probably weed out all the girls looking for an easy payday from a newbie.