(This post is more targeted towards freelance models and not those with agency representation, although it may apply to those that have an agent but continue to find their own work.)
A part of being a successful model is making money from the jobs that you book. However, being a freelance model comes with many challenges--figuring out what you should charge is one of them. I will say upfront that there are no established black and white rules when it comes to pay rates. Each modeling job is different, each client is different and budgets vary. Ultimately the factors that should influence what you charge should be the amount of experience you have, the strength of the images in your portfolio and the client's budget/needs. Not every client is going to pay what you want to charge. There may be times when you will be skipped over for charging too much or taken advantage of for charging too little. It's going to happen so be prepared for it and do not take it personally. It comes with the territory.
The level of a model's experience is a huge determining factor when it comes to pay rates. New and inexperienced models can expect to first undergo test shoots to build up their portfolio before charging for their services. There is no actual time limit or specified amount of years you need to be modeling before you can start charging. However, it is important to make sure you can walk the walk. For example, if you are a new model that has been modeling for a few months and done a couple of test shoots but want to start charging, you better make sure that you can work your poses and deliver as if you're a pro. If a client is paying you anything, they will expect the bar to be very high and if you can't perform, it won't be a good start to your career. So be realistic about your skills and ability when thinking about making the move from strictly doing test shoots to adding in paid shoots.
If you've got a ton of experience and the resume/portfolio to back it up, then clients will understand that using your services will come at a price. Of course not all clients that use freelance models will pay the going industry rate, so even if you have a lot of experience, don't expect to be making the same amount per gig that an agency represented model would. Are there clients that don't mind paying the industry rates to freelance models that agency models would normally receive? Of course but more times than not you'll be working with clients that have much smaller budgets--hence their need to use freelancers instead of models from an agency.
Some questions you should ask yourself when trying to figure out what to charge a client:
1. What is the client's budget? (usually they will state what they are willing or able to pay--minimum or maximum amount--or will just ask you what you charge for a shoot that lasts "X" amount of hours)
2. What type of gig is it: fashion, commercial, glamour, swimsuit, tradeshow? (swimsuit, glamour and artistic nude clients typically pay higher rates because of the nature of these types of shoots)
3. How long is the shoot? (quick 1-2 hour shoot, a half day, full day or multiple day shoot)
4. Are there any perks involved? (will they pay for transportation, lodging, meals)
5. What do you need to provide? (outfits, do your own hair and makeup, props)
Again, the pay rate for each potential gig should be considered on a case-by-case basis. There is always room for negotiation, which tends to work in your favor better than being too strict about what you charge. I've gotten gigs by stating what my rates were and then mentioning that I was willing to negotiate or compromise if my rates were outside of their budget. Or I will ask the client what pay range they felt would work for them and then decide how I felt about the proposed rate and if the opportunity would be worth going lower than my standard rates. If the shoot is going to be a full day (6-8 hours or longer) or requires travel, then you should stick to your guns and fight for fair pay. If the client is not going to cover transportation and lodging then you should factor those costs into what you would charge since those expenses will be coming out of your pocket. However, most clients have no problem with paying higher rates if they know the model has to travel and stay at a hotel overnight in order to work for them. But it isn't uncommon for a client to pay much less to models that are local so if you come across a great modeling gig that is within city limits but the rates are lower, you'll have to decide if it is worth it. They aren't necessarily trying to screw you over--more than likely they figure that if you're local it won't cost you as much to get to them so they may feel they don't need to pay a higher rate to compensate for travel costs.
Modeling pay rates can be per hour, flat rate or a day rate. If the shoot is short (1-3 hours), then an hourly rate is appropriate (i.e. $50 - $75/hour for models with a bit of experience and $75 - $100/hour or higher for experienced/pro models). For half day shoots (between 4-5 hours) you can charge a flat rate (i.e. $200 for models with some experience and $300 or higher for experienced/pro models). Full day shoots (6-8 hours or longer) should also be charged a flat rate (i.e. $300-400 for models with some experience and $500 or higher for experienced/pro models). If it is a multiple day event then you should charge a day rate, which should be negotiated with the client. This type of arrangement typically applies to tradeshows, conventions and similar events. The rates listed are just examples and may not necessarily "add up" the right way, especially if you're the type to break it down with a calculator. But then again, it's not supposed to. When it comes to pay rates and modeling, you can't always crunch the numbers the way you would if you worked at a part-time job or a regular 9-5. It is up to you to decide what you want to charge based on what is required of you and what the client will or will not provide.
Ultimately, the best piece of advice I can offer on this topic is to treat each gig individually and weigh the pros and cons. With time and practice you will eventually get a better feel for what you should charge and feel confident in the fact that you're worth the rate. If you find that no one will pay your rates you may want to step back and reconsider your price ranges if they are a bit too high. The economy has made things more difficult and does affect the modeling industry so keep that in mind. Are clients not even willing to pay you after you've dropped your rates? Then unfortunately, they are just trying to take advantage of your skills. Stick to your guns and continue to push for those clients that will pay.