I also start with value, using black and white pictures. That came with me to quilting from working with color in weaving. I am finding there are major differences when it comes to pattern. With weaving I am starting with color and texture and I pick the pattern by how I place color and what structure I use. With fabric, the pattern is already there and combining it along with the pattern of the blocks and then the overall look of the final piece is interesting. The design wall has helped with that, and again I take black & white pictures and move the blocks around til it works.