The “easiest and most ubiquitous way to get stuff out of your head is pen and paper.”
“… A paper notebook… is a walled garden, free from detours (except doodling), and requiring no learning curve.
“A growing body of research supports the idea that taking notes works better on paper than on laptops, in terms of comprehension, memorization, and other cognitive benefits.
Source: Why Startups Love Moleskines, New Yorker
Or put another way, sketch and make notes in your sketchbook, don’t only take reference photos.