I think figuring out what art supplies you need for painting anywhere is very important. I think putting those art supplies in a portable bag or box might be the next most important thing. The 3rd important thing for successful anywhere painting is knowing a little about drawing and watercolor painting, say maybe 5 drawing and 5 painting techniques, that's all.
Last of all you need the right attitude. You have to develop the attitude of looking at each of your paintings as practice exercises like practicing your scales to learn to play the cello. After you practice a while you are able to play a simple tune. If you can look at your painting and sketching with this attitude, and if you can locate your supplies and they are slimmed down enough to be portable you can do it.....by it, I mean paint and sketch wherever you find yourself.
I’ve put all the above into the class I will be teaching in San Diego, this Sat. at Artist and Craftsman from 10:30-1:30. Email me to register email@example.com