1. Painting from life will avoid the garish or washed out colors that are very often present in a photograph. Even perspective can be wonky in a photo.
2. Keep your kit as small as you can to keep it in a dedicated backpack, ready to go. If you are painting, bring just the primary colors (blue, yellow, red) and white - or a warm & cool of each. (4 - 7 tubes/containers)
3. Get into the habit of sketching your motif (a thumbnail of your scene) - bring a board or firm surface on which to rest your sketchbook or paper. A small portable easel with the ability rest a board or your sketchbook will help. A tray or board (your palette) to mix paints is required when painting, too. There are many pochade boxes to choose from that have easel abilities, storage, and a palette. Pochade: comes from the French poche or pocket.
4. Plain graphite pencils, &/or watercolor pencils, will do for sketching. And an eraser. Or bring water soluble graphite (this link shows just one type of many available) or charcoal for ability to make more varied marks. For painting, bring one or two brushes in the smaller sizes. I usually clean my oil brushes when I get home, so I dab them off with paper towels in the field.
5. Bring water to drink & enough for watercolor/graphite use and clean-up and paper towels or rags.
6. A view-finder to zero in on your scene is handy, and narrows your focus. You can make one from cardboard.
7. Simplify - use your view-finder to sketch a simple "thumbnail" that you can paint or even draw from.
8. Just know you will be overwhelmed. I think most plein air painters are.
9. Breathe, relax and just do it!
