As you're honing your skills with video, you may, at some point, be asked to do freelance video work for someone else. You know as well as anyone that video production is a skill that has value, so when you're asked what your rates are, you'll want to be ready with a number. All too often, new videographers are, for some reason, eager to work for free in order to build their demo reel. DON'T DO IT! Unless it's for friends or family, your potential client is surely expecting your services to cost something.
FreelanceSwitch.com has put together an hourly rate calculator to help you determine what to charge. Now, this calculator is designed for individuals who are planning on doing freelance work as their main source of income, but even if you only plan on doing video here and there on the side, there are a few take-aways here. The main one is that you should charge for your equipment. Even if you're okay with not charging for your time and labor, your camera and editing system in order to work, and being able to pay your credit card bills or business loans ensures that you'll still have your gear the next time you want to shoot.
One thing that FreelanceSwitch.com's calculator doesn't account for is rented equipment. If you're renting your camera and lights, I'd recommend using the calculator to figure out your rate without the rented gear, then putting together a work order and tacking the price of the gear on there. So let's assume you're not still paying off your camera, you really love doing video, and you have all the time in the world. You really should charge something reasonable anyway. The reason why charging for you work is important is because every time someone does video work for free they are devaluing the market. Think of the producer that was passed over because the client was sure they could get someone new to videography to do it for free. You might be in their position some day. This kind of thing happens all the time with video, graphic design, and art. It's a side effect of these fields to be really fun to work in!