Hey there, talk with an accountant and attorney. To protect you from liability, set up either a corporation or LLC. Depends on your state. In AZ, it costs almost nothing to set up an LLC and get a business license, but the laws in your state may be different. As a sole proprietor or just as a line professional, you expose all of your personal assets to any business liability. A corporation or LLC (limited liability company) limit your personal exposure to liability created by doing business - if someone sues you, they won't get to come after your house and car. Nothing is ironclad though and you need to talk with a lawyer for your specific situation. Trust me, the money you spend now on legal fees and articles of organization can save you 1000% in the long run. Be smart and talk to a business lawyer - many will consult with you for free knowing you will use them for something else in the future - just ask. I have actually called attorneys and gotten good info - I hire the guy later so it was good for him.
Liability insurance isn't bad to buy. I have a $1mm policy that costs about $85 a month. It covers me for all sorts of stuff like damage to a property while in a shoot. If you are going to shoot on someone else's property, which we all do, you should have it. You never know when a client will get litigious. You still need protection with releases and contracts, the liability ins just helps.
Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293