*Singles Expo. If you're looking for "an opportunity to meet where you're all there for a common denominator," declares Elliott Jaffa (best known for his Open University class--and style--"Chutzpah 101"), the Washington Singles Expo, on March 12 at the Shoreham Hotel, might be that opportunity.

The common denominator for the 30 or so mini-seminars: single-life issues. The topics, most of which have been offered by a variety of instructors as Open University classes, represent a virtual sociological smorgasbord: "Going Out Alone," "Single Bliss," "How to Pick Up Men/Women," "Travel for Singles," "Cooking for Singles," "People--Where They Are and How to Meet Them" and "Real Estate for Singles."

People come to these things "to meet interesting people," says Jaffa, 38. "I hear 'I want to meet people' over and over again in my classes. I offer them a nontraditional, humorous, common-sense approach to meeting men and women--where people are afraid of taking risks."

About 100 have signed up so far for the 9 a.m.-5 p.m. event. Cost is $40, plus a $3 registration fee, which includes coffee and donuts and one drink and hors d'oeuvres at the 5-8 p.m. cocktail party in the Marquee Lounge. The buffet lunch is extra: $12. Cost of the cocktail party only: $10. For more information: 966-9606.

*Singles Conference. Meanwhile, Georgetown Connection owner Joan Hendrickson announces that she has booked the D.C. Convention Center for the National Singles Conference the first weekend in April 1984. "We're expecting 10,000," says Hendrickson, "and we'll hold it to that number."

Response to the national conference (originally known as Singles EXPO) has been "outstanding," says Hendrickson, 49. "We've received over 1,000 letters from people who are interested in attending.

"Single people have been ignored. We want not only to identify what the problems are, but come up with ways of dealing with them. We want to show that singles are a strong political, economic and social group."

The overall conference fund-raising goal is $350,000. Several corporations have made commitments, she says, and more are being solicited.

One major purpose of the conference will be the founding of The National Association for Single Persons, an organization to provide ongoing support for singles in dealing with insurance, travel, taxes, lobbying, housing and "aloneness."

"Give them a reason to get together," says conference coordinator Hendrickson, "and by God, they do."

For more information, send a self-addressed, stamped envelope to National Singles Conference, c/o The Georgetown Connection, 1656 33rd. St. NW., Washington, D.C. 20007.

*Single Parents. The Home and School Institute's "National Conference on Single Parent Families and the Schools" is scheduled for March 24 and 25 at the National Education Association Center, 1201 16th St. NW.

Single parents, educators, mental-health professionals and social-policy planners will focus on these key questions: "Are families with single and/or absentee parents at risk?" "If 'at risk,' what is being done and what can be done?" Emphasis will be on exploring ways to build on the strengths of these families. Cost of the conference: $95. For information or to register, call 466-3633.

Author/pediatrician Dr. Benjamin Spock will address the conference at 8 p.m. Thursday, March 24, in a special lecture open to the public. Admission is by advance reservation only: $6 per person. To reserve, send an SASE and fee: Home and School Institute, 1201 16th St. NW.

*Money and Meeting. "Conversations," whose Sunday-afternoon financial-seminar format was originated last fall by Bethesda businesswoman Joan Farrell, will now be headed by business professionals Robbie Motter and Sandy Mueller.

"We want," say the partners, "to hear what you want out of the organization." They plan meetings every other Sunday, one with a speaker and the other purely for fun and sociability.

Selecting a personal computer for the home will be discussed by Sharon and Richard Short of Integrated Office Concepts at 4:30 p.m. Sunday at Asti Rosetto's, 7940 Wisconsin Ave., Bethesda. The first social, with music by pianist Ron Smith, dancing, sing-a-long and "conversations" is set for 4:30 p.m. March 20 at Hospitality House, 2000 Jefferson Davis Hwy. (Rt. 1), Arlington.

Fee for either event: $15 per person. Reservations necessary: 698-7480.

*Separations. A three-part self-help workshop for recently separated men and women is scheduled from 8 to 10 p.m. on three successive Fridays, March 11, 18 and 25, at Potomac Psychological Resources, 1225 Martha Custis Dr., Alexandria.

The leader is Carol Randolph, founder and director of New Beginnings. The workshop, she says, is a "crash course" in dealing with the practical and emotional issues involved in separation. It covers the stages of ending a relationship, handling new and ongoing relationships and legal issues. To register: 379-9520.

New Beginnings, a non-profit mutual-support organization for separated men and women, was founded by Randolph 3 1/2 years ago. About 138 members, ranging in age from mid-20s to 60s, meet in small groups in people's homes throughout the area. Two topics are offered three times each month on issues related to separation and divorce. Membership: $20 for 6 months; $30 for one year (subsequent fee: $15 for 6 months; $25 for a year).

"It's helping people get through that first year of separation that is so important," says Randolph. "People tend to think they are the only ones going through it.

"Most people tend to stay about two years in the group. It takes three years to really get over a divorce."

For more information, call 587-9233, or send an SASE (with your phone number) to 612 Kennebec Ave., Takoma Park, Md. 20912.