Why do I need an agent? Probably it is better to save money on agent’s commission?
In most cases it is wrong. If you want just to fool around and pretend to be a model, go ahead - be a freelancer. But if you are serious about your career, find a good agent!
Why do you think all supermodels and famous actors have agents?! Just think about!
One important point: We are talking about the honest professional agents.
Do agencies ever finance models material?
Modeling is a business. If you don't have or do not want to invest the required capital it is almost impossible to become a professional model.
The ridiculous statement that agents will pay for your photos if they like you is in most cases not true. Most agencies require you to pay for headshots, composite cards, headsheets, and photoshootings. However, some big agencies can loan money to very promising newcomers.
Before you go to any agency or sending them your photographs try to get as much information about the agency as possible. If you live not very far from agencies make phone calls to agencies and ask if they have open calls or you need to set up an appointment. Always bring your photographs in at the appointed time. Very often agencies ask you to send them your photographs prior they invite you to visit them. In this case you need to make several copies. Before sending your photographs put your name, address, phone number on the back of each photograph.
If you live far from agencies, you have to send a letter and ask for appointment. Also include copies of your photographs.
Do not make a very usual mistake: Never ask an agent just to evaluate your modeling potential. Always show that you are interested working with that particular agency. Several nice words about that agency can be useful.

What are the legal requirements for models from foreign country to work in USA?
You will need an American Model Agency certified by the United States Department of Labor to sponsor you for an H1, B3 Visa. If your Visa is approved you can work legally in the United States for up to 3 years. Visas can be renewed. You must be a model of "international acclaim". This means you must have modeled in other countries. Generally the United States Immigration and Naturalization Service will require tear sheets from several magazines you were in. If you have never been in any magazines, it is considerably more difficult but still possible.

What is the best protection against phony modeling agency?
The best protection against losing time and money to a phony modeling agency is to take precautions before signing a contract or paying anything. Check out all claims made in agency advertisements, sales presentations, and literature. For example, if they say they are the largest modeling agency in the country, contact other modeling agencies and ask if this is true. Ask for the names, addresses, and phone numbers of models who work through the agency and clients who have used its models. Contact the models and clients to verify the information. Ask if the agency is licensed and bonded, as is required if they claim they will find modeling work for you. If you sign a contract, be sure to get all verbal promises in writing. Keep a copy of your contract and all other important papers, such as agency literature.
You may need these if you have a dispute with the agency. If you cannot verify the agency's credentials and the agency is asking for money in advance, you may be better off saying no.

Do not believe promises of work!!!
If a prospective agent tells you he or she can book you for a particular film, video or modeling assignment, beware. Unless an agent is unusually powerful in the business, the most that agent can do is send you on auditions and put in a good word on your behalf.

Read info about modeling scams.