If you were to use the Turbobid product, like I talked about in your other thread, at the end of the process of putting together a bid the final product that is spit out of your computer is a very legalistic looking "contract" that requires a signature by both parties.
That said, if you were to use TB and end up with a computer generated contract, I would have a lawyer read it over and see what their thoughts are before presenting it to the contractor.
On one job that I wanted a contract for I used an online template (Rocket Lawyer.com). I think I originally googled contractor related contractual agreements, or something like that. It had a free 30-day trial and required a monthly subscription. I used it for one job, then paid for the next month then cancelled since I didn't use or need it anymore.