On the top painting, I looked for the main directions on a complex piece of drift wood and thought of how I would place it on the entire rectangular space. Then the drawing was quick roughing in a generality of the gestural directions of the wood. Then with a big puddle of color made on a palette, I filled the negative space around the drift wood. Next I put in some more pencil lines trying to define the borders of the high light areas, the mid tones and the darks. After mixing several grayed down colors on the palette, I painted the values leaving the lightest light the white of the paper with the little speckles of neutral colors from the conditioning of the paper before the painting was started. Last I put a shadow under the drift wood and when some of the paint was used up, I warmed up the gray with a small amount of brown and added a few brushed lines to indicate the grain.
Less finished is the second painting started with defining the values of the wood itself. Then when that dried I put in the surrounding negative area. I did not finish the picture because the value changes in the wood are not strong enough considering the darkness of the background.
So obviously I am a better judge of how the painting is evolving if I paint the negative areas first. But of course experienced watercolorists can have their own process of painting suited to their expressive style.