Use of Strips
Even understanding the subtle turning of form on a sphere can be difficult. But by simplifying the sphere into large planes that define its structure one can gain a less complicated realization of a form's structure.
The section on the sphere outlined in red represents a strip of form.
I have found painting in strip like sections of form to be very helpful in gaining a better understanding of a form's structure. I began modeling the sphere by simplifying a strip into a few distinct planes, as shown in the image on the left. Then I simply turned each of those planes into into each other to gain a more subtle curve of form. I would continue painting small strips of form next to each other, using the same process, until the entire form was painted in.
Simplifying Complex Forms
The study of part of an ear cast above was painted in strips of form.
Each strip of form has a specific orientation to the light. To more easily comprehend each strips orientation to the light one can imagine an axis running through each strip. By imagining each strip being pulled on its axis, as if the axis was a lever or handle, one can more easily approach investigating the curving of complex forms.
A step by step diagram, left to right, of strips being turned by their axis to make up a complex form. Since I was working in strips while painting the ear study above this is the thought process that I was using to simplify that complex form.