I've never worked in gouache before but have always been intrigued. It used to be a go-to for mock-ups in the advertising industry and also for children's book illustrators. It is water soluble, like watercolor, but opaque instead of translucent. When I received my set, the fun colors reminded me of getting a fresh box of crayons as a kid.
I squeezed a little of each color into an airtight paint box and wanted to work quickly using a palette knife, not mix colors, and try not to overthink it.