I have been working as a freelancer for years and have always been paid, that said it is worth taking a few precautions.
As a freelance cameraman there are a few things you can do to ensure you get paid. There are preventative measures you can take to ensure you are working for the right people, but if things go wrong and clients refuse to pay, there are also tactics that could help you get the money you are owed.
Most people will tell you to make sure you have a contract with your employer, however, in the world of TV, this is pretty unrealistic. If you are working a contract over a few months you may get a contract, but for most short term jobs an email or phone call might be all you get. This being said there is plenty you can do to protect yourself.
If your job offer is just a telephone call, getting it in writing is a good idea. Even if you just email them back to confirm the rate, the hours, the number of days etc, you will have a contract of sorts and proof you have been employed to do a job.
If you don't know the company, do a little research. Do they have a habit of not paying people? Are they easy to contact? Do they have a physical address? All of things will help you access the company when you need to get paid. If it is a big contract you could even ask around and find out what other freelancers say. I would always be more cautious of working for an individual, as companies tend to be easier to contact when it comes to getting paid.
If you aren't sure about the company, ask for payment up front, or maybe ask for half of the fee and the other half on completion. When I am asked to work for a company based abroad, I always ask for the fees up front, the reason being it is much harder to take these companies to court or even contact them if they decide not to pay. I find companies are happy to pay up front as they understand the risk involved.
Be clear about your payment terms and stick to them. I give 30 days as this is standard in the uk. After that date I will remind the client. I always remain friendly and professional as I understand companies may struggle with cash flow, or may have simply forgotten the payment. I usually want these companies to employee me again, so it doesn't make much sense for me to send Joe Pesci around to their accounts department with a baseball bat.
What happens if you do the work, but don't get paid?
Firstly, it is worth being persistent. Find the right accounts contact and email them. If you still haven't receieved the money after your payment term, gently remind them. If you still don't receive anything it is worth calling to clear things up, just to make sure they haven't lost the invoice or paid it into the wrong account. Although 30 days in the standard payment term, some companies may regularly wait two or even three months before they pay freelancers to aid their cash flow. Although this is frustrating there isn't much you can do about it, other than email them reminders.
What if they refuse to pay you? If you still don't get paid, then you may want to lean on them a little harder, this is a last resort as it will certainly destroy your working relationship. The footage you shoot is your intelectual property, which you are selling to your emplyeer. If they don't pay you, then that property is still yours. This is a point you could easily make to the broadcaster or brand or whoever the end client is for this material. Obviously this is going to cause a major headache to whoever employed you and they may find it prefereable to just pay you what you are owed.
What if this still doesn't work? It is worth remembering that governments want business transactions to run smoothly and for individuals and companies to get paid. Whatever country you live in, there is probably some sort of system that can help if you aren't getting paid as a freelancer. In the UK there is the Small Claims Court which deals with small amounts of money owed (under 10,000 UKP). Although this sounds like a lot of trouble, especially if the amount of money you are claiming is really small, you may not need a solicitor or even have to go to court. Just registering the claim online means that a court date is set and a letter is sent to the person or company who owes you money. The letter alone could be enough for your client to pay up, as they may not want to go to court.