In recent years, there's a rise in freelancers for fields like photography, design and programming. Falling equipment prices and powerful online tools made it extremely easy for anyone to start their own freelance operation. Like with everything else, your approach and mentality towards freelancing is very important and will greatly affect its outcome. Here are some thoughts on how you should freelance.

1. Price - This is the number 1 reason why companies hire freelancers. Since your costs and expenses are lower than a normal business, you can afford to charge lower. But this is a trap. If you charge too low, you'll end up de-motivating yourself when it take longer than usual to complete. Try to charge a reasonable price that you are comfortable with even when things don't go according to plan.
2. Specifications - You need to have the specifications of the gig written down in black and white. It is hard to cover everything but at least there is a reference for you and your client when an agreement can not be reached.
3. Quality - I think this is the most important factor that determines if your freelancing endeavor will be successful or not. Due to pricing and specifications issues, a lot of freelancers ignore the quality of their work. They adopt the get it done and move on mentality. The quality of your work will be remembered long after your pricing is forgotten. Read this piece from Seth on how freelancers can make a difference.
4. Proper documentation - This is an extension of the 2nd point. Try to provide all the necessary documentation to your clients. It will make you look professional and protect you from troubles later on in the project.
5. Run it like a business - If you could only adopt 1 of the points here, let it be this one. You have to consider yourself as a business owner. Show that you are doing this for the long haul. Form a company if you can and start building your brand.

Obviously this isn't an exhaustive list. There are many other things you could do to make your freelancing better and more fun. As long as you have the right mentality towards it, you'll be alright.