I've got lots of these sitting in a portfolio. I used gouache (think of it as opaque watercolor) on many of them. Often I do two and three at a time. While there are times when I use this a warm up exercise, the majority were done because I just love painting on this paper.
The paper is very absorbent and not very forgiving. If I use a lot of water, I have to be careful not to scrub too hard with my brush because it will disintegrate.
More to come...here kitty, kitty!