I ride as far to the right as practicable, which I define as being as far to the left as necessary for my safety. That particular point varies depending on road conditions.
On the part of my commute where there is a wide shoulder, to the right of the fog line, that is where I am. On the part of my commute where the shoulder is non-existent (on a portion of my commute there is no shoulder, just 2 travel lanes and a 6 inch high curb) I ride in the right lane, right wheel track. When I need to turn left, as I approach the intersection, I check traffic, signal if necessary, then get in to the left lane, right tire track.

On the two lane (rural) portion of my commute, my road position varies depending on the surface conditions, pot holes, cracked asphalt, glass etc. There is a portion of my commute where I am almost on the yellow line because of road surface conditions. I also tend to ride a little more to the left on the fast downhill sections of my commute.
When making a left on a rural road, as I approach the intersection, I go from the right wheel track to the left tire track.

I believe that taking the lane makes me more visible, and also signals that the driver needs to execute a proper pass as opposed to trying to squeeze by me in the same lane.

I would recommend the LAB Traffic 101 class for the OP.