Help with a Limited Liability Contract?

I am starting a summer business in which i switch people's old incandescent light bulbs with Compact Fluorescent ones (CFL's). I need a contract that limits my liability in their home and with any problems that could arise working in their home. (Anything from a CFL breaking and requiring clean-up, to something more expensive in their home breaking.) I'm new to this, where is a good place to look for a contract that I can piggyback off of? Preferably for free.