Everyone knows about the art they should have bought 10 years ago. The question is, what do you buy now?

If money is limited -- but the passion for collecting is not -- the Bethesda Art Gallery is still one of the best spots on the East Coast to re-discover American prints from the '20s and '30s, one of the hottest sectors of the art market for the past decade. Its current "New Collectors" show (at 7950 Norfolk Ave., Bethesda) is designed to help newcomers get into the field, even though prices have now spiraled to the point where real bargains have become rare.

The gallery's Douglas Duffy has also recently been part of a big-money print-collecting project that focuses attention on the extraordinary status American prints of the period have attained.

Duffy was called in as one of a number of top print experts to advise a collector on how to buy the 100 best American and European prints of the last 100 years. Of the 46 artists named most often by the experts, nine of the top 15 were Americans from the '20s and '30s -- amazing, if you consider the fact that nearly every American print on the list could have been had for a few hundred dollars, or considerably less, only 10 years ago.

(But the task of defining the 100 best prints proved impossible, said Duffy -- 420 different images were nominated. The single print named most was Picasso's "Frugal Repast.")

David Williams, a New York financial manager who presided over the deliberations of the group, has some advice for beginning collectors: "Buy something. There's nothing like spending some money to concentrate the mind. It encourages interest and attentiveness, and that's how you learn. And that's what it's all about."

Though the show in Bethesda contains a few lesser examples by big names that made the list, like Howard Cook, the better buys are -- as always -- among the lesser-knowns, notably Jay McVicker, Washington's own Prentiss Taylor, Harry Shokler and Isac Friedlander, a superb wood-engraver and etcher who happened to be Joseph Hirshhorn's cousin. The show continues through April 20. Andrew Krieger at Gallery K

New talent is the other traditional route for beginning collectors of art in general, and Andrew Krieger, now at Gallery K (2032 P St. NW), should be high on any list. He works in an unusual format: small, intimate boxed environments -- often corners of empty rooms -- cut from white paper, with every meticulous detail drawn in with graphite or ink. One recent kitchen-corner piece, titled "7 A.M.," is populated, but by a futuristic robot who appears to be fixing breakfast for herself.

Other works in this show seem to take off from there. Abstract cutout forms appear to be close-ups of body parts for such robots, which he calls "Prototypes," "Futurotypes" and, in the case of several drawings incorporating biomorphic, phallic shapes, "Small Muscle Involvements." His oddly mechanistic forms are rendered both in flat drawings and in boxes. One of the best is "Prototype IV," which seems to be at once the ancestor and the descendant of a typewriter. The show closes March 30. Scenes of Glen Echo Park

Great art teachers are not only hard to find, but often unsung -- especially those who labor in the area's public schools. One of the best and most admired is Walt Bartman, who has taught for several years at Walt Whitman High School in Bethesda, as well as at the Corcoran School of Art and now at Glen Echo Park.

A show of work by recent Bartman students is currently on view at the Glen Echo Gallery -- an appropriate setting, since Bartman has been prowling the park with his classes for years, using it as both subject and inspiration.

"In and Around Glen Echo" includes only a few fine loosely painted views of the park (and one of Bonfield's gas station) by Bartman himself. The rest of the show belongs to his charges. But the difference between his work and theirs makes the point that he's not out to produce esthetic clones. Rather, he is known for teaching his students to see and to develop sufficient skills to release their own energies. There is great variety in these student scenes of the old carrousel, the ballroom and Trav's road house, and considerable daring in a view of the dusty old parking lot. Among the budding talent, Ann Lofquist, Ben Warren, Danielle Berlin, David Asofsky, Rosalyn Joffe and Jeffrey Easton stand out. The show continues through April 1, and is open Saturdays and Sundays noon to 6 p.m., and weekdays 10 a.m. to 5 p.m