I've admired 
Nathan Fowkes' sketchbook studies and wanted to try this myself because I tend to be in a big hurry to get into my painting, without doing some preliminary work ahead of time to insure a better composition. So this weekend I played around with gouache and watercolor on some scrap papers.
On Saturday, I worked on the following three compositions. These were from a picture I took in Sedona about 6 years ago. The paper for these were cut about 5 x 7 and masked off with artist tape.
This was done on pink matboard, probably not the best color, but it was just an experiment. I signed with an opaque white paint marker, but it still wasn't dark enough for me.
This was a similar composition and view. I like the black paper much better.
This was on an oatmeal color cardstock - reminds me of butcher's paper.
I like the pencil for the writing. I like this piece the best. 
So, yesterday I got the brilliant idea I needed more colors in gouache. I bought a few colors of grey and a sepia. It didn't work out at all. I think the range was too close on the greys and the sepia too dark for that range.
This is something I want to master - if you can  view/create something in grey scale and the composition works, then it will work  well in color.
 The following abstract piece was just playing. I had started a scene from a picture at  Inniswood, but it just looked terrible, so I just started slashing colors on the  paper. Just wasn't working out yesterday for some reason. I think I need to  simplify the subject matter.