If 1985 promises to be your year for a new job, making a few New Year's resolutions can help turn mere promise into real prospects. And, contrary to the longstanding myth that active job hunting during and immediately after holiday seasons is bad timing, employment consultants say no time is better than the present.

A survey conducted last month by Drake Beam Morin Inc., an international career consulting firm with offices in New York and the District, compared monthly success rates for 2,700 job seekers during the past three years. January ranked first for finding new employment.

Job vacancies increase this month, according to William J. Morin, chairman of the firm, for three reasons: Many employes delay resigning until after they've collected December bonuses; the end of the year is a popular time to retire and many companies wait a few weeks to fill those positions; and new corporate budgets begin in January.

But taking advantage of employment opportunities now and throughout the year "requires discipline and setting definite goals," says Jack Erdlen, executive director of the Employment Management Association (EMA), a national, nonprofit organization of employment and personnel executives, headquartered in Wellesley, Mass. Erdlen recently asked EMA members to recommend New Year's resolutions for job hunters. The most frequent responses:

* Make five or more new contacts daily, including friends, acquaintances, employment agencies and help-wanted ads. Persistence and the law of numbers works.

* Continue to answer classified ads from newspapers and magazines, even box-number ads. It's easy to get discouraged -- but thousands of people are hired through help-wanted ads each year.

* Prepare a separate cover letter for each ad response. Avoid becoming mechanical. Tell the prospective employer why you qualify for the advertised position, using the ad's buzzwords to describe your interests and credentials.

* Consider a worst-case situation when planning a job search. What will you do if you can't find a job in your preferred geographical area? How different from your ideal job are you willing to deviate? You can always decline an unsatisfactory offer.

* Follow up with contacts you haven't spoken to in a month or more. People hear of jobs regularly, but they'll assume you've found a position if they don't hear from you.

"Everyone agreed on the importance of determining goals and objectives," says Erdlen. "Making and keeping resolutions . . . helps to avoid a hit or miss approach that can be detrimental to job hunting." More New Year's Cheer

* A recent poll of nearly 2,000 executives responsible for hiring in companies throughout the country predicts that employment opportunities will improve during the first half of this year over the fourth quarter of 1984.

Of those polled by Management Recruiters International Inc., a national employment search firm, 42.1 percent said they planned to expand middle-management and professional staffs during the first half of this year, compared with 35.9 percent six months ago. Staff hiring in the South Atlantic region, which includes the Washington metropolitan area, is expected to increase by 2.6 percent, lagging slightly behind the national projection. Checkup Workshops

Having doubts about your job choice or career progress lately?

The University of Maryland Career Development Center will offer career checkup workshops that emphasize your attributes in determining "how you can enhance your career/life effectiveness," says Bruce Ritter, alumni career consultant at the center.

Participants will take the Myers-Briggs Type Indicator test and attend three Saturday sessions. Price is $60 for alumni, faculty, staff and grad students; others pay $75.