Looking for a contract for my contractor

[Colin Williams]

Hello Bigger Pockets family. I am trying to get my rental fixed up to be sold and I'm wondering who I should speak with about getting a contract written up that protects me from losing my money. Is there a place I can find an review contracts and pick one that fits my situation, or should I go to an attorney? What type of attorney would be best? Do they typically have generic contracts that can be tweaked? 

The contractor sent me a contract built on Rocket Lawyer, and he's asking for 50% deposit for the work. How should I go about negotiating those terms? What is a good pay structure to be used. The work should only take about a week. Consists of repairing holes in walls and replacing flooring and the front door frame and door. 

Thank you you all very much.