What She Did

She may have come off as a lovable ditz in Annie Hall, but Diane Keaton is savvy about flipping real estate. A board member of the National Trust for Historic Preservation, the Oscar-winning actress is known for meticulously gussying up old California abodes and selling them to the likes of Madonna. She recently continued her streak with a stunning twofer, selling two homes, a 1920s Beverly Hills manse and a house designed by Lloyd Wright (son of Frank), for a total of almost $21 million.

How She Did It

Keaton's coup required some serious elbow grease. At the Wright home, she restored the designer's built-in furniture, upgraded the kitchen and knocked down walls to create a loftlike master bedroom. She brought in interior designer Steven Shadley to collaborate on the other project; they replaced medallion-dotted fireplaces with simple, white-plaster ones and turned an entryway into a library. (Keaton, who bought both homes in 2007, declined to be interviewed, but public listings confirm the renovation details.) Even after expenses, local experts estimate Keaton came away with a profit of about $1 million, over a period when the local market was down more than 20 percent.

What You Can Do

Orange County, Calif., real estate agent Markus Brown says old-home buyers can imitate Keaton by "capitalizing on the nostalgia" instead of staying 100 percent true to the original design. Getting rid of smaller rooms typical of the older style but keeping nods like vintage doorknobs and color schemes can make homes more attractive.