Lately I've been rotating forms in my head and trying to use that as a way to explore and study planes. Its is very fun and worked well when I'd do line drawings, but I was having real trouble as far as painting goes.
an old acrylic got eaten up to make this
Painting is different from pure line drawing in that you explore the opposite functions in a way. As far as a line goes, mainly it serves to go around the edges of forms and planes, and when it goes around the edge of a form, that is a surface that is curving away from the viewer. But in a painting you explore the surface that is facing the viewer. I know I know, line drawing does some of that too. Especially with shading, and paint explores edges that curve away. I think though that line is primarily about edges while paint is primarily about surfaces of planes. So in a way they overlap but cover those ends of that spectrum.
dunno how you see while wearing this
I realize what I was missing while I was painting is that when you rotate the forms and place them in the scene you have to see the light on the surface, and study how it looks. It was easier in line because I could just see the planes and draw lines around them, but in paint you've got that other element of color (value/hue)... I'm not that good at it yet, but i feel better :)