I constantly see this question: "I am a model. How much should I charge?" This question generally comes from amateur- and freelance models and most of them actually think that there is a one-size-fits-all answer to this question when in fact there isn't. While agencies work with fixed rates and fixed commissions, the rates for freelance models can range anywhere from $0 to $infinite. Generally, a model's rates are dependent on the model and his or her market (location). As in all business, the price is determined by supply and demand. Ideally, the price is set where supply and demand cross to reach an equilibrium. This is economic theory, but everyone who does business should be aware of the effects of supply and demand. If there is more supply (here: the model) than demand, the price is lower. If there is more demand than supply, the price is higher.
Market Competition As a model, it is important to determine one's own value and compare it with the competition in the market. There are several factors that will determine ones own place in the market: 1) How does your look and your stats compare with other models in the market? While "look" is a very subjective issue, there is also something very objective about it. A 5'10" model with a perfect facial bone structure and perfect measurements will generally be able to charge a higher rate than a 5'3" model with bad skin and a round figure. When you look at different kinds of photography, you will quickly see that there are looks that are more marketable than others and can hence command a higher rate. 2) What kind of experience do you have with respect to modeling? Models are mostly hired based on their looks, but it can help to have experience and a portfolio to show for it. Personally, I like models who know what they are doing and who understand the commands a photographer will give them. It saves time for everyone involved and adds more personality to the pictures, so it's a good selling point. 3) What kind of photography are you available for? Certain types of photography, such as fine art nudes can command a higher rate than other types of photography where the model does not take off her clothes. Some photographers call this stripper rates, but in the end it's just the supply and demand cycle all over again - Less models are willing to pose nude, so there is a smaller supply which increases the price.
Each market is different and that is something you need to keep in mind when setting your rates. See how you compare with other models in your market and charge accordingly. The above list should help you determine your own position and if you can charge more or less than average.
Negotiation Basics When a photographer contacts you about a shoot, you will most likely either quote your rate or enter into negotiations. Quoting a rate is the easiest thing to do, but it may cost you work or money. The one who quotes a rate first is usually the one who gets the short end of the stick. Let's say a photographer has a budget of $150 for a four hour shoot and your rate is $300 for four hours. If you quote your rate first, the photographer will probably not hire you. Now let's say that a photographer has a budget of $600 and your rate is still $300. If you quote your rate first, the photographer will hire you, but you only get paid half of what he budgeted.
Agency Competition In addition to other models, there are also agencies who you compete with on pricing. It actually amazes me when I see agencies charging $50 (+20% commission) per hour and freelance models in the same market charging $75 per hour or more and complaining that they do not get any work. It just does not add up. Freelance models have a much lower overhead than agencies and hence should be charging less if they do not have as much work as they want to have.
Target Market Most photographers that are willing to pay freelance models are amateurs and hence you should consider the amateur photographers your target audience. Most professional photographers go through agencies and it's usually the client of those photographers who pays for the models. The reason for professionals of going through agencies is simply the expected level of professionalism. Amateur models have a reputation of being a risk factor because they may flake on a shoot. With amateur photographers, that risk does not come at a high cost except for time. On a professional shoot on the other hand, a model that does not show up may incur thousands of dollars of costs in rental equipment, wages, etc.
Conclusion It is hard but not impossible for a freelance model to make a full-time income with modeling. Nonetheless, even though there are no agency requirements for freelance models, models that conform with a certain look will largely do better than the ones that do not. Most amateur models who do not have an outstanding look will find it almost impossible to make money without taking off their clothes. That should not discourage you to at least try. Just keep in mind to do your research beforehand and be wary.