If you seek to break in to the business of modeling, you must look out for untrustworthy people. Some people are looking to steal from you, selling you on a great career in exchange for payment. When all is said and done the only thing you'll have is an empty wallet.
Here are some warning signs that you have to be aware of.
1. Classified ads. If you notice an flier posted somewhere - in a newspaper, on a chat room, etc - then think twice before responding. Successful talent agencies have lots of ready talent, and they don't really need to look around. You may want to respond to open casting calls, but elsewise forum posts like these are a bad sign.
2. Asking for payment at the beginning. If the talent agency charges you money up front before you can be represented by them, then gather your things and get the hell out of dodge. This is a clear hint that they can't be making money on modeling gigs, so they instead make revenue elsewhere. If they aren't making money, then neither will you.
3. Making you use their in house photographer. A big talent agency will tell you to get a set of images together along with some comp cards, but they shouldn't force you to drop a ton o' cash on their own photographer. You can compare and select a photographer or comp card printer who you approve. If they really want a specific photographer, then they'll foot the bill.
4. They want you to pay to take their modeling classes or whatnot. It's yet another way for them to make money. It might seem more noral than a "signing fee" or something. But when you really look at it it's the same thing.
5. They guarantee you jobs. If only it were that simple. No one can guarantee that you'll get a real gig as a model, and anybody that promises that is just trying to sweet talk you. Chances are, they're trying nudge you into offering them some money.
After you've heard about a handful of these scamsters, they become simple to see for what they are. The simple idea is that the agency wants to bring in as many potential models as possible, drain their wallets up front, and in the end throw them a few bones with a few open auditions. As long as people keep coming in the office, they don't lose sleep because you're on the street not working. They made their cash. Don't let that cash be yours.