Preparation

I used to reject the notion of doing value sketches before doing a painting.  My rationale was that I could see the values in my head, so why do a sketch?  Then one day when I was teaching a workshop, I asked my students to do a value sketch.  One student did a light, scribbly line drawing with no clear darks, midtones or lights.  I took her sketchbook and turned her non-descript drawing into a sketch with very clear values.

With the values in place, you have a road map to how to proceed. Light values first, midtones next, and darks last.  In this sketch, it's also pretty clear that distance will play a role.  Far away tones in the background, midtones on the churches' shaded sides, and darker cast shadows in the foreground.

I've also learned to love taking my sketchbook everywhere I go.  I can almost always find something to turn into a sketch.  Looking out the window at lunch at an old Victorian house across the street and sketching it gave me a way to pass the time until my order arrived.

Proclaim your status as artist!  Take out your sketchbook!