“Buy an artist who is out of fashion,” suggests Gary Metzner of Sotheby’s. More specifically, look for those who are working in a trending genre but have fallen out of the spotlight—for example, William Conger and Susanne Doremus, forerunners by several decades of the young abstract painters who are currently all the rage. “They’ll resurface,” says Metzner.

So will styles—such as the op art of the ’60s—that are no longer getting much museum play, and thus cheaper.