Like Goldilocks, there is a lot of trial and error involved in this whole plein air undertaking. The first two big questions that seem the most daunting are:
1. What do I need as far as supplies and setup?
2. Where is a good place to paint?
So here are some quick notes on my misadventures. I'm summing up three trips.
First try
Beautiful spot, but right as I finished setting up, a few hornets chased me away! They seemed really interested in my paints... why was that? When I got home I put two and two together: half of my plein air pallet consisted of M. Graham pigments. This company produces lovely paints but uses honey in their formula - not so great for the outdoors. Curious bees and hornets will certainly be interested in your work!
Second try
Beautiful spot near a favorite hiking trail, with wide fields dotted with stately trees. The shade from a giant pine was very welcome, though I had a hard time figuring out what composition I should paint. It seemed like everything I knew in the studio flew right out of my brain, even how to paint trees. I left after two attempts, wondering what went wrong.
In hindsight, it is probably easier when starting out to pick a spot that has an obvious subject to help with the composition. Some good composition basics to watch for would be small clumps of trees, large rocks, or interesting water features like a stream or lake. Really practiced painters have this amazing ability to rearrange things in their mind, but for beginners like myself it is a better recipe for success to have the scene pre-arranged.
Third Try
Perhaps I have found the golden spot at last...
Rock formation? Check. Non-hornet paints? Check. Lasting light? Nope.
Luckily I was quick on the draw with capturing the shapes and doing my best to color match, but it turns out that color matching while the sun is setting is a bad combo. I am happy with the way the paintings turned out this trip, though when I took the picture there was no more light warming the face of the rocks like I tried to show in my painting and I simply ran out of time. I was very happy with the blues and greens that seemed to translate.
Keep and swap: Keep my easel with extendable legs for this uneven terrain, swap my honey-based paints.