I'm becoming more and more aware of how important it is to have an idea (not necessarily visual, but a theme, a word, a concept) that will then inform every aspect of the rest of my drawing.
It seams one of the best ways, for me at least, to capture an idea early on is to use small denotations of anatomy.
So if I am trying to draw a child I will use small tick marks to show the relationship between the eyes and the nose. Once I see that bunched up set of proportions then I know I'm drawing a child and build an informed shape based off that. Then I proceed to uncover the form as quickly as possible so I can have a more solid concept to inform the rest of my drawing.
I'm really curious what other peoples thought process are on this. In what way do your early ideas come to you, and how do you capture them so you can transform them into a specific form?