There are some safe routes to follow in the search for reputable firms and workers that can help steer homeowners away from shoddy home-improvement jobs, unfinished work or cost overruns.

The size of the job you want done will determine what sort of trades person you need. If you want to add a closet to a bedroom or have built-in bookshelves put in your living room, you will probably want to hire a carpenter who specializes in small jobs. However, if you want to close in a porch or add a room to your home, you will need a contractor.

When looking for someone to do the small job, keep in mind that many people who do this sort of work are not licensed or bonded.

Licensing and bonding gives the consumer a measure of protection, but is not an absolute guarantee of reliability and competence. In the case of licensing, a local government has a record of the business address and can trace the owners if it becomes necessary. Bonding requirements and coverages vary from jurisdiction to jurisdiction, and it would be wise for a homeowner to check with a consumer affairs office or the appropriate office of the local government to be sure what is covered.

Unlicensed contractors are sometimes called "shade tree" operators, they work out of the back of a truck and have no office or business address. Often they will want to be paid in cash, which can pose a problem for homeowners who have no written receipts for work done. This can be difficult to explain at tax time.

Such workers are likely to charge lower prices, but you always take a chance when hiring them. It can be difficult to settle disputes over their work, and local governments are unable to offer much help in tracking them down.

If you decide to hire someone who is not licensed and bonded, be sure to check references carefully--including bank references. Be skeptical if the person asks for a large downpayment. Unless you have checked carefully, you run the risk of never seeing the money or the work.

Many workmen who operate without a license are trustworthy and do good work, but you must check references to be certain.

For bigger jobs, you need a contractor. He will "orchestrate" the job; that is, hire the electricians, plumbers, painters, etc. He will also take care of getting the proper permits and scheduling the work and inspections.

Perhaps the best and easiest way to find a good contractor is to ask neighbors and friends who have had work done. You may hit it lucky.

"Our biggest boosters are people we've done work for and who are proud of the job," said A.O. Kresse, president of Kresse & Sons, Inc., a Potomac home-construction contractor and member of the Suburban Maryland Home Builders' Remodelers Council.

The word-of-mouth route is often the most reliable way to find a reputable contractor. One young man got his start by sticking flyers advertising his work under the windshield wipers of cars in a shopping center lot near the area where he worked. He received several calls and has worked in the same subdivision on various jobs from references for nearly two years.

Another way is to check with local trade groups such as the Suburban Maryland Home Builders Association, a chapter of the National Association of Home Builders. This group now has a Remodelers Council made up of members who have such experience. They operate under a code of ethics and promote professional standards and sound business practices among their members.

The trade group will provide consumers with a list of several contractors who do the kind of work being sought. They will not recommend a contractor, but will provide names of members who do the sort of work being sought.

Consumers should also check with a Better Business Bureau or a local or state consumer affairs office to see if there is any record of complaints or problems with contractors. The few minutes it takes to make the calls could save trouble later on.

Newspapers are also a source of contractors' names. Some papers will take ads only from businesses that are licensed and bonded. Their business license numbers must appear in the ads. Consumers should know, however, that the business license is just that--a revenue or tax license. It is not a guarantee of an individual's qualifications to perform work.

Carpenters are different than plumbers and electricians who must pass an examination testing their occupational skills. Bonding also means that in case of a legal dispute legal fees will be paid. It will not pay a judgment and does not pay for performance and completion of work.

Consumers should avoid dealing with people who indicate they have been working in the neighborhood and have extra lumber, roofing material, etc. and can give them a good price on work to be done right away. Likewise, they should beware of the sales pitch in which the consumer's house will be used in advertising or promotional material. If approached by such sales people, ask for a phone number where they can be reached if a decision is made later to have the work done.

Similar caution should be exercised when responding to a Yellow Pages advertisement. Many businesses listed there could be in financial trouble. The current poor economic times will force many to go out of business. One contractor estimates that the average life of a small firm is 1 1/2 years.

Howard Simon of Jamar Construction Co., Inc., and a member of the SMHB Remodelers Council said, "Be careful of people who say they will do the work on weekends or in the evenings. That's a good clue that the job is not their full-time work."

Simon warms, "Too many people shop price. They may be able to get the work done cheaper if they use unlicensed workmen, but if something goes wrong, they have no recourse."

He cites an example of a job his company had done about 18 months ago. A dormer was added to a house and made into a bathroom which began to leak through the ceiling of the room below. Simon gives a one-year guarantee, and the leak occurred six months after the warranty ended. He repaired the work and absorbed the cost.

He has a satisfied customer and a reputation that earns him a referral rate that accounts for about 90 percent of his business.

"I've done three different jobs for one family, two for another," said Simon. "When I give references to prospective customers, I also will give the name of someone who had something go wrong and which I've corrected."

Simon has been in business for 30 years.

There are other things to keep in mind when doing the preliminay checking on a contractor according to Howel Mole of Add-A Room Construction Co. "Always ask for references, and go see the work without the contractor around. This will give you a chance to question the person who had the work done."

Mole, who has been in business since 1970, recommends consumers ask such things as how long the work took, how much the remodeler charged, and whether there were any problems during the job.

"Remodeling is a complex process," said Mole, "All sorts of things can affect the way the job gets done."

Weather can become a problem if the work requires opening a roof or exterior walls. Remodeling can be dirty, too. Be sure to discuss any special problems with a contractor before work is begun--noise or allergy problems, etc. Such things can affect working relationships and make a difference to both the homeowner and the contractor.

Mole also suggests that consumers get several references--not just one or two--and see all the work.

Having decided upon a contractor or carpenter, the next subject is likely to be how much the job will cost.

For small jobs that are relatively straightforward, it should be fairly easy to compare prices. If you get several bids that are in the same range, you can be fairly confident that the averagge bid will be what it will cost. Be skeptical if you get a bid that is unusually low. If it sounds too good to be true, it probably is.

On larger jobs, you may want to get competitive bids. This will require a complete set of plans and specifications prepared by a professional architect or designer.

Professional contractors recommend the consumer know as much as possible about the work they want done. Changing ideas in midstream can be expensive and exasperating for both the homeowner and the contractor.

Asking for a cheap price is asking for trouble, according to Howel Mole. "You are asking to be cheated if you make a decision on price alone. There are all kinds of ways contractors can cut corners."

A.O. Kresse said, "a contractor can cut 15 percent to 20 percent off a price, and no one will ever know. Generally, a homeowner can't judge quality and won't know he's being taken advantage of."

Once a contractor is chosen, payment terms must be worked out.

"Legally a contractor is entitled to one-third of the price at the beginning," said Kresse, "Often they will take it, partly out of self-protection."

Simon suggests, "Work out a payment schedule as the job progresses."

There are some stages in the work where payments might be made. For example, after the foundation is in; then another payment might be made when the framing is finished; another when the roof is on and then when the interior is finished.

Some contractors will take only an advance payment on work if special equipment is to be used, such as plumbing fixtures that are special orders from a manufacturer.

Kresse recommends that consumers ask the contractor for a certificate of insurance or the name of his insurer. The proof of insurance will be supplied by the insurer and will show what type of coverage is carried by the contractor. This is important because if he does not have workmen's compensation, the homeowner could be hit with a lawsuit if an accident occurs. No reputable contractor will be insulted if he is asked to provide such evidence.

Any contractor who asks a homeowner to arrange for a permit is certain to be unlicensed. This should be a clear warning signal that the person is not complying with local regulations and could mean trouble later for the homeowner should something go wrong with the work.

Written contracts are important and should be well written and clear to the homeowner and the contractor. The quality and quantity of material to be used as well as style and band names should be included, according to John Morton, a suburban contractor.

He said, "Get the contract spelled out exactly. You cannot be too specific. Contractors are liable only for what is in the contract.

"For instance, a phrase about bringing work up to applicable codes or better should be included. You should be specific about the number of coats of paint you want, for instance. It's too easy for workmen to cut corners, saving in their costs and shortchanging the customer. They can be long gone by the time the consumer finds out the work as done improperly."

Here are some sources of help for the homeowner:

* "Tips on Home Improvements", a pamphlet available free from the Better Business Bureau of Metropolitan Washington, 1334 G St. NW, Washington .

* "How to Choose a Remodeler on the Level," a pamphlet available free for single copies by writing The National Association of Home Builders, Attention: Remodeling and Rehabilitation Department, 15th and M streets NW, Washington 20005.

* "How to Remodel," a free pamphlet from the Washington chapter of the National Home Improvement Council, which will also supply a directory of its members who are improvement contractors. The phone number is 638-0079.

* Suburban Maryland Home Builders Association, 1717 Elton Rd., Silver Spring, a local trade group that will supply names of member contractors (434-6800).

* The Northern Virginia Home Builders Assocication will provide names of member contractors who do remodeling work (893-6800).