I love painting outside. It's my preferred way of creating work and I create a lot of work during the summer season because of this. Here's a few of my favorite things that I take with me when I paint:
Heavy-bodies acrylics: a limited palette
Goache Paints: Since they are small I like to take my whole set as it fits in my box nicely.
Neo-color Crayons- my favorite for quick sketches as they are water soluble
1-2 Long handled brushes varied in sizes. Longer handles help keep my paint strokes loose and relaxed.
Pencil and Sharpener
Lastly: my polaroid camera. It helps me capture the exact light and shadows I'm painting in the moment. That way if I get pulled away from a piece I'm working on, I can come back to it later.