The way I've always preferred to work, even when I take a photo of a place or thing, is from sketches. There is something about simplifying an image down to lines and shadows that helps me to create something that feels a bit more 'painterly' to me. I can get bogged down in details, so removing those details really helps. The final image isn't usually a replica of a place but rather a painting of the feeling of that place. It helps me to loosen up. Whenever I have worked directly from a photograph I find that I become so critical of my painting that I can't get past making constant adjustments. I will occasionally refer back to a photograph, but more often with the purpose of viewing colours rather than replicating an exact image. It's that part of the creative process that I enjoy so much.