I have to agree with the "it depends" concept. At one intersection of two two-lane streets, I took the lane (no cars behind me), signaled a left turn with my arm out, and while waiting for oncoming traffic to end, a car passed me on the left to go straight through the intersection. Now I avoid that intersection, but it taught me that even when behaving like any other vehicle, you do have to be very alert. There are bad drivers everywhere.

At the main left turn on my commute, it is again the intersection of two two-lane streets, no left turn signal, lots of oncoming traffic turning right. I wait for cars to pass me and then get into the main lane and stick my arm out. If there are no cars, I take the lane and then let them stack up behind me. The biggest problem so far has been oncoming cars turning right who have carreened through even though I'm turning, and then left me on their left side. I saw one car/driver who did that again later, and she still seemed to be oblivious to everything around her.

Make eye contact whenever you can; it's hard to know if you have, but look straight at the other drivers and they will sometimes wave you on, so you can clear the intersection first. When they do that, wave back. It's only safe if noone is whipping around from behind them, though, which happens a lot here.

The more predictably and car-like I ride, the better it seems to be. I also try to make eye contact and smile, nod, or wave at any traffic cops I see.