The black and white sketches are value studies , done as a plan before undertaking a painting. Shari put me on a colour diet and I only had three near primary colours to work with. This is also a good way to achieve unity. This was a great exercise as it was also a jump from my little travel kit of hard pans to tube paints which where different hues from those in my kit.
The planning sketch also inherently addresses composition - not only fitting the whole subject of the page, but how to lead the eye and provide a point of interest. I think I'll start doing 2" x 2" blocking studies on the left (backside) page in my sketchbook prior to starting a sketch. if nothing else it should keep me from running out of room on the page for the whole subject, as I sometimes do.
I brought away several other very practical little reminders and techniques to use as I continue to try and figure out to make watercolours work.