HELP WANTED. SALES. Temp. P/T, F/T. Flexible hours. No exper. necessary . . .

The frost may not yet be on the pumpkin, but Washington-area stores are already looking ahead to the Christmas rush and are hiring thousands of temporary salespersons. Some will start work immediately; others will report in after Thanksgiving.

You may be tempted, as I was last year, to apply. Among the advantages for people who can spare 15 or more hours a week:

Variety of shifts.

The range in work hours can suit the schedules of moonlighters, housewives, college students. The period of employment can be as brief as three weeks or as long as four months. Most stores still need their seasonals the week after Christmas, when malls are jammed with gift exchangers and bargain hunters.

Career opportunities.

"Temporary" does not necessarily mean "dead end."

Thirty to 40 percent of Woodward & Lothrop's seasonals ask to stay on each year, and 10 to 20 percent are offered permanent jobs.

"Well over 50 percent of the company's permanent workforce, including upper management, started out as temporary employes," says Joseph C. Culver, vice president for personnel.

Unlike Garfinckel's, which accepts only college graduates for management training, Woodies and Hecht's train promising employes for management positions regardless of educational background.

"It depends on the person," observes David Nellis, Hecht's vice president for public affairs and customer service. "There are people who have MBAs from Harvard and can't cut it. Other people who have only a high school diploma can."

Dependent to some extent on the economy, prospects for employment in retailing look bright. The U.S. Department of Labor predicts that jobs in the field will increase by as much as 28 percent during the 1980s.

Previous experience unnecessary.

If you are a job hunter with nothing to enter under "previous experience" on your applications, working as a seasonal will give you both experience and references.

Employe discount.

"Associates," as department stores call their employes, develop mental calculators capable of computing instantly their discounted prices on any items. Most stores offer 20 percent. The discount helps to compensate for the usual small salary, which brings us to the disadvantages of these jobs:

Low pay.

It makes no difference whether you are a high school student or a college professor with a string of advanced degrees; if you have no previous selling experience, you will probably receive the minimum wage, $3.35 an hour. And believe me, you will earn it.

Fatigue.

Expect to stand for as long as four hours at a stretch. Working in a department store last year, I never sat down except during breaks.

Stress.

"I haven't had anything to eat since 8 this morning, when I had a piece of toast and a boiled egg," moaned Peggy at 3:15. Feet propped up, we were trying to unwind in the employe lounge after four hours on the floor.

"I'm hungry," she went on, "but my stomach hurts from nerves."

With her youngest child in college, she planned to return to work as a secretary after 18 years as a full-time homemaker. This temporary job would provide recent experience. Even though we had 12 hours of training on the terminal, we still got finger-tied when confronted with a tricky exchange or return.

Adding to the stress: the Christmas countdown with increasingly edgy shoppers and longer lines. After playing bit parts in my customers' Christmas preparations, I had little time or energy left for my own.

Missing Christmas.

Seven days before Christmas, my cards remained stacked on my desk, unsigned, unaddressed, unstamped.

Before you apply for a temporary job, remember Christmases past and the activities you usually get involved in. Your job may not leave time. How many are you willing to skip?

Other considerations in deciding where to apply: Type of merchandise sold.

Choose a store with merchandise you want to buy. Your discount, which you should consider as part of your salary, will not do you much good in a toy shop if there are no children on your gift list.

Your hobbies and special interests.

If you are knowledgable about photographic equipment, electronics, computers, books or sporting goods, consider a shop dealing exclusively in this merchandise. Your expertise will increase your chances of being hired, and you will feel at home in your surroundings.

Ambiance.

Keep in mind you will be stuck in your store for many hours. Think about your reaction to the lighting, decor, background music. For some people, continuous high-volume rock could make an already stressful job unbearable.

By now you probably have a list of places to apply. Decide what shift you prefer and whether you are willing to work weekends. The sooner you apply, the more likely you are to be hired and assigned to the shift you want.

Call the stores and ask whether they are hiring, or simply report to the personnel office during business hours. But do not even go near a personnel office unless you are dressed for an interview. You may be interviewed immediately after filling out an application.

Remember, unless you have sales experience, the impression you make -- not education or unrelated employment -- will determine whether you are hired. The interviewer must be able to picture you out there on the selling floor neatly dressed according to the store's standards.

What else will the interviewer consider?

"We are known for the service we provide and want salespersons who will go a little out of their way to help," says Marilu Seckinger, Garfinckel's director of public relations.

Woodies, according to Culver, hires "the type of individual who feels comfortable dealing with the public . . . and can work well under stress . . . self-confident with an easy conversational style."

"I look for someone who's fairly articulate, able to express himself or herself reasonably well, someone who wants to work for JCPenney," says Margaret Hughes Baldwin, personnel manager of JCPenney's Annapolis Mall store.

The interview is your opportunity to obtain useful information. Some extra questions you might ask:

"What are my chances of staying on?" (If you're interested in permanent employment.)

"When could I expect a raise?"

"Is there a ceiling on the total price of purchases to which the discount can be applied? Is the discount the same for all merchandise?"

"Will I be asked to work extra hours?"

Although temporary employes usually have no desire to become permanent, many return year after year to the same store at higher salaries. For them, helping people with their Christmas shopping has become a tradition.