I use a terms of business instead of a contract as the word contract scares alot of people. It covers areas such as the client or its subsidiaries cannot use ex-employees of mine without financial cost to themselves as I had a big problem once of an ex-employee nicking my work. Both client and myself have to give a minimum 1 month notice. Non payment of invoices and what happens ie. interest rates charged. Also on health and safety it states that if the client sees my employees working in an unsafe manner they can call a stop to the works. I put in 2 copies of terms and conditions (1 them, 1 to be signed and sent back to us) in our new client pack which has copies of all company policies in it ie. customer complaint procedures, environmental, health and safety, anti-discrimination, working on site rules, etc., copy of insurance policy, work schedule and obviously costs. personally I think can save misunderstandings if everything written down, even if never used at least it is there.