Do not allow a contractor to inspect your property when you are not home and watch them during the inspection.
Always obtain more than one bid for the project/repair.
DO NOT give a contractor Power of Attorney over your affairs, or permit them to negotiate or settle your insurance claim.
Make sure you read and understand your contract before signing it. Contract should include: A thorough description of the work to be done and specifies all materials to be used; a start and completion date; the total cost; a payment schedule; any warranties and guarantees of workmanship; the method for debris and material removal; the type of work you expect; includes the contractor's full name, address, phone # and business license number.
Verify all necessary permits are obtained.
Pay contractors by check or credit card, rather than in cash, so you have a record of all payment issued.
Do not pay a contractor in full, or sign a completion certificate, until all work has been finished.