I recently took a painting workshop in Grass Valley with artist Denise Wey (http://www.denisewey.com). She makes good use of a monochromatic underpainting for her river paintings. Although I have tried this in the past, I have never really used it on a regular basis. I realized in the workshop, that this was the perfect way for me to get over my problems with value. I always struggle getting a good range of values and I find it particularly difficult working in color. For these two paintings I created a monochrome underpainting to the point where I was mostly happy with the values. Then I used thin glazes of color to complete the painting. I used a lot of acrylic matte medium and very little paint. This enables you to sneak up on those values and create wonderful depth. This is especially effective with water - something I have not had much success painting before.