Hm don\'t tell your Teacher that shes a foolish person,
The artcolege im going in has transportation design class it\'s world famous, at least among car Designers, those guys are the eliete working vor mercedes, porsche gm and blah... these guys also did this stuff when they got started its about focusing your mind, drawing is seeing and understanding, once you focus your senses youre much more open.
Another thing is this baisic shape stuff its worthles, its something you should take care after you managed your first steps.
While focusing on baisic shapes, youre not realy observing the object, your just squeezing it in some shapes.
Some Loose doodle is often a much better sketch. A Line has an expression try to play with it, good linework makes 50% of a drawing
Theres a nice book I dont know the english title but the author, betty eddwards, it explains how your mind works when you draw and how to practice it.
But this all is theory, get yourself a sketchbook and sketch averything you got in sight(no photos), after a while your way of seeing things will chnange...
and the more you draw the better you get ^^
gl hf =D