I think that it might be less confusing for the newbies on the roundabouts to quit thinking in terms of right turn and left turns. Just learn which lane you are supposed to be in to go the direction you choose. Logically, all turns from the circle are "right" turns. The exits are one through four. Regardless of which direction you enter from, your first exit is YOUR number one, the two, etc. The signs posted at the approach to each roundabout are very clear.
Also, no lane changes should occur once you are in the roundabout. You are either inside our outside.
Never enter a roundabout beside another car. Stagger your entry so that you are not T-boned. Also the speed limit of 20 is absolutely necessary. It is not an arbitrary speed.