What does writing have to do with painting? For the dedicated painter, especially a beginner, it serves to nail down what just happened, to take the daily experience of painting outdoors and looking closely at it to glean the most benefit from it. You just spent hours battling bugs, cold or heat, fatigue, and oil paint in order to complete a painting on location Now you’re done, comfortably sipping a cup of hot coffee, most importantly, sitting down and just staring, happy you did what you set out to do.
Now what, just go about your chores and distractions of daily life while your experience and all you learned fades into last weeks memories? You can do that. But a good practice is to sit down sometime the day of the paint out and jot down some notes on where you went, what you painted, size of canvas, and any notable things that may have happened during painting. Also, a quick critique of the painting is a smart thing to do, along with a resolution of what to do or not do next time around.
For that purpose, choose the kind of journal notebook that appeals to you. Perhaps a simple spiral-bound will do, or you may want to use a blank ledger/journal notebook like the one show here. They come with a ribbon for marking your place. They have hard covers and lined paper. Make it a habit to write in your painting journal after every painting and keep up this habit as long as you like, but at least for a couple of years. It isn’t recommended to “write”, just make notes. Don’t worry about making it a piece of literature. In fact, just assume that no one but you will ever read it.