What material are you printing with?

One thing you can try is to use thinner layers, that should make the steps on the overhangs less wide so you don't print so much in the air.
Besides that you can try using support structures or cutting your object in half and print the top and bottom separately and then glueing them together.

You can run some tests with a calibration object like this one: http://www.thingiverse.com/thing:58218
With my printer, using PLA, a 0.4mm nozzle, 0.25mm layers and plenty of cooling that test prints fine up to the 25 degrees overhang, 20 degrees have some defects and at 15 degrees I get a stringy surface.