There are a few intersections on high-speed roads where I'm reluctant to get over into the left-turn lane, and often will do the right-turn + U-turn routine, but for the most part, I do turn left like a car. You need to start thinking early and often you need to get left way earlier than seems reasonable.

When you're going straight approaching an intersection, and a car wants to turn right into your path, the thing to do is make yourself more visible. Be assertive and ride farther out into the lane. This is also helpful for helping you prevent a right hook.