I have never tried gouache before. This 5×7 of the Gallatin River in Montana is my first attempt. I could probably spend some more time to make it a little better, but I am not sure I have the patience today. Still lots to learn about this medium.  This was done with Holbein gouache–Prussian Blue, Burnt Sienna, Yellow Ochre, and Titanium White–on Fabriano Tiziano blue paper.