contracts???

[FIREMAN]

I am concerned with the need for contracts on residential and commercial deign/build projects. Where should I seek advice on the proper wording and content to make contracts binding? Also when signing a new job how do you generally outline payments? I have been generally using this, 1/3 before any materials are ordered/purchased,1/3 half way through and 1/3 on completion, sometimes if a project is materials heavy, I specify more up front. I ask this after being burned for about 10,000 dollars last season on one job and having to pay an attorney to tell me the contract I had my client sign was not binding....