Imagine, if you will, the typical Washington consultant.

What you probably envision is a well-tanned, smartly attired fellow who whirls through your office - if you have an office - exchanging intimatices with the boss, asks innumerable questions about your work and seems only mildly interested in your answers, takes voluminous notes, and disappears.

A couple of years later, a massive report arrives in an attractive polyethylene binder, full of flow charts and systems analysis jargon - all of which is accompanied by a rather large bill.

Well, says Frank B, Tennant Jr., consultants are not really that way at all. They are not the "Beltway Bandits" they are made out to be. Not every consultant is rich or on the way to being rich.

"Consultants have a bad tendency to underprice themselves," says Tennant. "They forget about overhead orthey undervalue their overhead. They forget the cost of marketing their services." Worse yet, they forget to budget for the time they spend trekking around in quest of clientS.

Consultants, in short, are just folks. As such, they need advice and encouragement, and that is where Frank Tennant, consultant to consultants, comes in.

Twice a month, more or less, Tennant offers a $90 seminar on "How to Become a Successful Free-Lance Consultant." He gives his seminar up and down the Eastern Seaboard, but most frequently here in Washington, where the federal government is paying out about $1.8 billion annually for consultants' services, according to rough figures from the Office of Management and Budget.

A former career army officer and a specialist in television and public speaking, Tennant calculates he has put about 500 students through his day-long seminar, including the 16 current and aspiring consultants who attended Saturday's session at the Tysons Corner Ramada Inn.

Most of Tennant's students are engineers, computer specialists, systems analysts, health administrators, freelance writers and editors, and aspiring business and tax consultants.

Brenda Maiers, a former private school superintendent who now works at Gallaudet College, says she got interested in consulting when she saw some of the consulting grants the college was receiving. "Many of them were very easy to do," she says. Being a consultant, Maiers adds, is "more dynamic" than just being an employe.

Reginald Washington, vice president of a Baltimore community development corporation, wants to advise small businesses on financial problems. "When people hire a consultant, they want instant success," he says. "I have used some consultants before that haven't produced, and it really turns you sour against consultants."

Tennant's first advice is not to reject the idea of becoming a consultant simply because you have concluded you lack special expertise. "The expert riding in on the white charger saving the fair damsel" accounts for only about 5 percent of all consultants, says Tennant.

Consultants often are engaged because a problem is temporary rather than particularly specialized, he explains - or because an employer wants to avoid the travails of hiring, and firing, full-time staff. A consultant may be brought in to take the political heat for an unpleasnat personnel decision. That way, the employer cansay afterward, "We hired an expert and we only did what the expert said."

In any case, your skills are probably more numerous than you know, says Tennant. "Sit down with a pencil and a yellow pad and do an inventory," he suggests. "Go back to when you were a kid with a paper route or mowing lawns or whatever." There is just no telling how much expertise you may uncover in yourself.

Once you have hung out your shingle, the next step is to locate clients. If it is the government you want to work for, Tennant cautions that about two-thirds of all federal procurements ready has the contract lined up, But apply anyway, he says. Get to know the people who handle the contracting, and "down the pike somewhere a job may be wired for you."

Your banker can help you find a private client, says Tennant. Bankers have a way of knowing which businesses have cash-flow problems or need to raise quick capital, and consultants frequently are used for such purposes.

"Companies that are going up need capital," he says. "Companies that are going down need capital. I'd much rather see you associate with one that's going up, but there's an honest living to be made from a company that's going down as well."

If nothing else seems to work, you might just pick the most prestigious possible client and offer your services for free, says Tennant.

If the client accepts, you will have an impressive item for your resume.

All in all, Tennant regards consulting as a "beautiful profession... where a little gray at the temples is an asset, not a liability." At 47, Tennant himself shows no gray at the temples, but he says he has been a consultant for 14 years and a full-time consultant since his retirement as the Pentagon's chief of information in 1971.

When you do accept a consulting assignment, he says, take care to display tact in your dealings with the permanent staff. "Go around and say, 'Hello, I'm Joe Smith, I'm a consultant... I'm not here to abolish your job," Tennant suggests.

"Unless, of course, you are thereto abolish their job, in which case you have to use another approach."