Rotate 3d camera around 3d object

Here's my goto approach for creating an orbiting camera.

1. Create a null layer. 
2. Make it 3D
3. Position it to be where you want the centre of the orbit to be.
4. Parent the camera to it
5. Keyframe the null's rotation

You'll now get the camera orbiting around in a perfect circle.  You can still keyframe the camera's position, so you could push in to your model in a spiral pattern, for example.