Some feedback on your cylinders. When your drawing your wrapping lines, try to imagine a rubber band, going around the cylinder. It doesn't stop at the edge, it wraps around it.
Secondly - an elipse is just a circle in disguise. Whenever you have a section of form, that's going directly away from you. It's going to be a circle. As it turns away from you, the elipse gets narrower. Try finding a CD or a plate, hold it in front of you and then turn it in one direction and notice how the outline, gets thinner and thinner, untill you can only see the edge. When you draw an elipse around a cylinder, that "degree of turn" is what you're showing.
