How do you navigate traffic circles? – Share your tips

We spent the morning debating the proper way to navigate traffic circles, but the only thing we could seem to agree on was the fact that they're frustrating.

From Somerville to Marlton, it seemed like each circle has its own tradition. Some callers said you should yield to the people already in the loop, while others said people in the loop should yield to those entering it. Many strategies were hinged on the placement of traffic signs, but these signs probably aren't doing their job if we're still debating the right way to drive.

What's your rule of thumb for handling a circle or roundabout? Who do you yield to, and when? Share your tips for getting through safely by commenting below.