Warnings from both the Better Business Bureau and state government agencies caution homeowners against contractor con artists looking for a quick buck in the wake of a storm. In 2005, builders and contractors topped the list of categories for fraud complaints filed in Florida.

How can you tell a capable contractor from a polished pretender? Here's how to help ensure a good job before it begins:

Search for pros effectively. Choosing a contractor you liked before is your safest bet. Readers who hired contractors they'd worked with were happier and had fewer time and cost overruns than those who tried someone new. Those who hired pros recommended by a friend or neighbor were also more satisfied than those who hired strangers, though they had as many delays and extra costs.

Suppose you weren't happy with your last contractor or you've moved to a new neighborhood. Several good leads can help take the guesswork out of finding a new pro.

One is the National Association of Home Builders, an industry trade group that includes contact information for local builders' associations at www.nahb.com. Another is the National Association of the Remodeling Industry (www.nari.org), a trade group. Those groups' member directories can help you in your search. Roofing and siding companies such as CertainTeed, GAF, and others can also help you find local contractors who have been trained by the manufacturer to install their products. Some companies offer certification programs that require training, experience, licensing, and insurance.

Ask the right questions. Local contractors are likely to be flooded with work in the wake of a serious storm. But that is no reason to fall for a scam artist. There are several ways to spot a questionable pro right from the start. An address that can't be verified is an immediate red flag, as is someone who uses only a post office box or who has an answering service or cell phone with no separate listing.

Be wary of out-of-states plates. Unsolicited "contractors" who knock on the door with an offer to fix a damaged roof or windows may easily disappear once cash is in hand. Also be wary of hefty discounts with no mention of the total cost, as well as pros who want to use your home as a "demo" or claim that they're doing a job in the neighborhood and have leftover materials. Other reasons to keep looking: high-pressure sales tactics, threats to rescind a special price if you don't sign on the spot, and dire warnings that your house puts you at peril.

Once you've found a promising prospect, get references from older and recent jobs, and check the work to see how it held up. Then take these steps before you take the plunge:

• Ask previous customers whether they were satisfied. Seventy-eight percent of subscribers we surveyed said they were very satisfied with work done for a major home-improvement project. Fifteen percent said they were fairly well-satisfied with results, but 7 percent were at least somewhat dissatisfied.
• Look for proper insurance. If someone is hurt or a neighbor's property is damaged by an uninsured contractor, you could wind up paying. Get copies of the contractor's liability insurance and workers compensation certificates. Also find out what your homeowners insurance covers before work begins.
• Look for proper licensing. While that won't guarantee success, it indicates a degree of professionalism. You may find your state licensing board's contact info at www.contractors-license.org. (See Getting help in your state for licensing boards in hurricane-vulnerable states.) Some states and counties license contractors, as do many large cities and townships; others require contractors to be registered. Licensing usually entails passing a competency test, while registering involves only a fee. A government agency may be able to pursue a licensed or registered contractor on your behalf.

Also look for trade affiliations. Membership in the National Association of the Remodeling Industry (NARI), the National Kitchen & Bath Association, or the National Association of Home Builders' Remodelors Council also suggests a measure of professionalism. NARI will try to resolve disputes between member contractors and homeowners, if requested. Industry groups such as the Vinyl Siding Institute are raising the bar with training and certification programs.

• Consult Angie's List (www.angieslist.com). This free site provides consumer reviews of home contractors in 40 major cities, which can help assist you in your choice.
• Perform a background check. Call the Better Business Bureau (www.bbb.org), your state's attorney general's office, or a local consumer-affairs agency for complaint histories of the contractors you're considering. One or two gripes may not be a problem, but if the contractor has more than that, it could signal trouble.
• Get at least three written estimates. Be sure each bid includes a timetable and the specific products and materials you want as well as the labor. Material and product allowances should give prices and quantities. And don't jump at the lowest bid; readers who did generally got poorer work. A rock-bottom price could mean the pro is cheaping out on materials and excluding essentials.
• Decide which type of contractor you need. We asked more than 1,500 subscribers about their experiences with major home projects: finishing an attic or basement and adding an enclosed porch or room. Those who hired plumbers and other pros themselves were happier than those who left the hiring and supervising to a general contractor. Projects were likelier to be within budget and on time.

On the downside, you may not want the added hassle of acting as your own general contractor. These pros free you from such burdens as maintaining a work schedule, obtaining necessary permits, and resolving disputes with suppliers. They're also likely to have added leverage with subcontractors, especially those they use for other jobs.

A rule of thumb: If your job requires more than three subcontractors, a general contractor is probably a good idea.

• Get a contract without the "gotchas." A fair contract helps you and the contractor minimize misunderstandings and wasted effort. It should be dated and include your name and address as well as the contractor's name, address, and license and phone numbers. It should also include a timetable for starting and finishing; a payment schedule; names of subcontractors; the scope of the work; and a procedure for how any changes will be made. Other essentials:
• Be sure the contract lists what's included and what isn't. That means complete specs for materials and equipment, along with demolition and clean-up provisions and a clear statement of who's responsible for getting permits and inspections. It also means a clear list of extras, including any assumptions the contractor has made--that existing wiring and plumbing lines are adequate, that subflooring is sound, or that you will pay for all trash removal, for example.
• Stay involved. Surprises often happen once work begins. Be sure you're reachable during the day. Then set aside time with the contractor each morning or evening for a daily progress report.
• Get problems fixed before the final payment. Your contractor should agree to resolve problems during the course of work, rather than afterward, when the check has been cashed.
• Keep control of your money. Pay for the project in stages as key materials and supplies are delivered. Keep the down payment to a minimum (10 percent or $1,000, whichever is less). And don't pay in cash or with a check made out to cash. For major construction projects, consider having the contractor place the down payment in an escrow account. Then schedule the final payment for within 30 days of satisfactory completion of the project. Also be aware that contractors may get discounts at lumberyards and supply houses; the contract should cover whether or not those savings are passed on to you.
• Protect yourself legally. Watch out for binding arbitration provisions that limit your right to sue. And never make the final payment until you have signed mechanic's-lien waivers or releases from all subcontractors and suppliers. These are essentially receipts that acknowledge payment for goods and services and free you from claims on your property should your contractor fail to pay subcontractors or suppliers. You may also require an affidavit from the contractor stating that all subcontractors and suppliers have been paid and that the contractor is responsible for any liens filed.
• Pick products carefully. Americans spend upwards of $150 billion per year on home improvements. Years of testing have shown that choosing the right products can be as important as choosing the professional who installs them.
• Choose the product yourself. Roughly 75 percent of homeowners choose their own exterior house paint and stain. But when it comes to asphalt roofing and vinyl siding, most people still let their contractor do the choosing.

Significant performance differences in our roofing, siding, paint, and stain tests suggest that you, rather than the contractor, should decide what goes over and onto your home. Checking our Ratings is the best way to choose brands and models that deliver the performance you want at a price that fits your budget. (See our Home Improvement Guide for more information.)