This is my equipment for painting gouache sketches outdoors:
1.) Moleskine sketchbook with watercolor paper. The size and shape of this sketchbook is well suited for landscapes, and it works good for gouache.
2.) This is my palette. It has a lid, so I can close it, and the paint will stay wet. If I work on a bigger scale and more paint is required, I can also use the lid for mixing paints. I can close it, and put it in my bag without everything becoming messy with paint.
John Pike watercolor palette: LINK
3.) I use:
-a pencil, for my initial sketch
-a sumi-e brush for my initial broad washes. The shape of the brush has a lot of variation, which creates interesting shapes.
-two watercolor brushes for detailing and linework
-two square watercolor brushes for block ins
-two broad watercolor brushes also for initial washes
4.) -A water container. (I just see what old jar i have, and use that..)
-Gouache paints. I use a selection of basic colors. When I am on the spot to actually paint, I decide which colors will end up on my palette. I hardly ever use all the colors I take with me.
5.) An atomizer. It is filled with water, and I use it on my palette to keep my paint from drying out. I also use it for effects on my painting.
6.) A small chair, which makes it easy to sit wherever I want..
This is the complete package I carry with me when I go out to paint...