Lines:

1) Some of the lines in your ghosted lines and planes exercises are pretty wobbly. Possible reasons could be that you are worrying more about accuracy or that you're struggling to use the shoulder. In any case remember that having a smooth confident line comes before hitting the marks.

Ellipses:

1) In the funnels exercise, some of the minor axes are off the line of symmetry of the ellipses, just make sure the minor axis goes through the centre line of the ellipse.

Boxes:

1) Same again, with the lines

2) Try being more dramatic with the perspective in organic boxes.