Don't pay cash, don't let the payments get ahead of the work completed, and don't pay the full cost of the job up-front.

Under state law when undertaking a home improvement or repair job, contractors cannot ask for a deposit of more than 10% of the total cost of the job or $1,000, whichever is less . . . unless the contractor provides a bond, approved bond equivalent, or approved joint control ensuring completion of your contract. Any such bond is in addition to the bond required of all contractors for licensure.

Require a written contract with the contractor's license number on it, and don't sign until you fully understand the terms. Remember, if it's in the contract, you can expect to have it done. If it's not there, even with a verbal promise, you may not get what you think you are paying for.