Nationwide, the single largest source of complaints to consumer and licensing agencies is home improvement contractors. But whether the job you want done is installing hurricane protection, redoing your kitchen, or a renovation of your entire home, you can dramatically reduce your risk of getting stuck if you follow some basic rules.

Figure out ahead of time exactly what you want done and when you want to do it. Deciding to redo a bathroom is not enough. Decide what fixtures you want to put in. Ask yourself if you’re going to redo the walls and floors—do you want tile, marble, granite, Corian, sheetrock or a combination? Once you’ve signed a contract, changes in the plan can be costly and limit your recourse if there is a dispute. Plan changes are where even honest contractors make their money.

Get recommendations from friends and neighbors who’ve done similar jobs. Don’t just go by ads in the newspapers and phone books. Also, don’t feel that you’re obligated to use a contractor just because a friend recommended him.

Get at least three estimates, but before you ask a contractor for a bid, check him out. While I’m not enamored by the Better Business Bureau, as they seem to favor their member firms, their Web site, www.bbb.com, can show you the number and type of complaints filed against a company and give you some background. Crooked companies go in and out of business fast, so look for a firm that’s been around at least three years and compare its complaint record against the other firms you’re considering. Just having some complaints should not necessarily rule a company out, as this is a tough business and homeowners are not always right or fair. But make sure you see how the complaints were rectified.

You should also check with the state, www.myfloridalicense.com, or county, www.building.scgov.net, to see if the contractor is licensed. No matter how much of a bargain you may get, do not hire an unlicensed contractor. There’s probably a good reason he doesn’t have a license, and you may find later that the work isn’t up to code, or was done illegally and has to be ripped out and redone. Also, the license gives you some place to go if the work is done improperly or not at all.

Check references. Ask the contractor to give names of satisfied customers and call them. Ask them if the job was done on time, in a workmanlike manner and for the agreed price. Then ask them if they know anybody else who had work done by this firm. You’re more likely to hear of problems from these referrals than from the people given you by the contractor.

Get a written estimate. Too often the contract price is higher than the price quoted, and unless you had the estimate in writing, you’ll find that you “heard incorrectly” or “misunderstood” some of the terms.

Get a contract that shows the project in complete detail—work to be done, materials to be used and detailed drawings showing size and location. Read the contract and strike out any terms you won’t accept. Contract forms used by home improvement contractors have been prepared by their lawyer or their association and invariably favor them. No contract language is carved in stone. If you don’t like it, strike it out. If the contractor won’t change it, find another contractor. I think that contracts for large sums of money should be reviewed by a lawyer, but nobody wants to spend money for that until it’s too late.

Get a firm starting date and a firm completion date. I always ask the contractor how long the job will take, and then add a reasonable length of time onto that to get a completion date for the job. Put in exact dates, followed by the sentence, “time is of the essence.” This means you and the contractor agree that if he doesn’t complete the job as promised, you can seek recovery in court. It doesn’t always work that way, but it gives the contractor something to think about when he gets another job and wants to leave you hanging. Do not accept “A.S.A.P.” as a date. The contractor will tell you that this means “as soon as possible.” In fact, it means that you are A SAP if you accept this nonsense.

Make sure the contractor has a permit for the job. Work done without a permit can incur the ire of the local building department and can require the work to be undone. Sure, the contractor can tell you that a permit increases the cost and brings around pesky inspectors, but unless you’re an engineer or architect, this is the only protection you have against sloppy or dangerous work.

Do not pay for work before it is done. If the contractor has gotten his money in advance, his need to finish the job is severely diminished. When he gets another job somewhere else, he’ll be off your case like a rocket. All of a sudden, his truck will break down, his workers will get sick, a supplier will have ordered the wrong materials, a family member will die or some reason will come up to explain why your job has to be delayed.

If the contractor doesn’t have the money to perform your job, he is not reliable enough to entrust with your money. If he does the job and you don’t pay what you owe, he can place a “workman’s lien” on your house to enforce payment. Until the lien is settled, you can’t sell or even re-mortgage your house. He knows where you are—where are you going to find him if he doesn’t complete the job? In other words, the contractor has plenty of security against your defaulting. The only security you have is the money you are holding pending completion of the job. You should always owe him money until the job is complete.

What if you follow all these rules and still get stuck?

First, document your complaints. Take pictures, get statements from witnesses and, if necessary, hire an independent expert to review the problem. Second, put your complaint in writing and keep a copy for yourself. Verbal complaints aren’t worth the paper they aren’t written on. When push comes to shove, you will find that phone calls you made and conversations you had never took place. You don’t need certified mail or return receipts, but they can be impressive. (Under the law, a letter placed in the U.S. mail is presumed to have been delivered.) Third, call or write the licensing authority. If your contractor has a state license, check the Web site listed above for complaint procedures. If the work was done under a county building permit, contact the county.

Contact the Better Business Bureau. They can’t force compliance, but they can try to mediate and also list the complaint on their Web site to help other homeowners. Don’t worry about losing the friendship you had with the contractor. That friendship was a one-way deal, anyway, and went out the window when he messed up your job.

And if all else fails, call the lawyer you should have hired in the first place.

Before he retired to Sarasota, attorney Howard Tisch provided legal services to the Attorney General of the State of New York for the bureau of Consumer Fraud and Protection and served as Deputy Commissioner of Consumer Affairs for the City of New York.