Sketching onsite is a very relaxing and freeing experience.  It requires letting go and relaxing in the moment – of becoming one with the scenery before you. When it isn’t possible to work on site, my suggestion is to take great pictures to work from later.  Sit outside in a lawn chair or at your drawing table, enjoy your favorite coffee or tea, and start to sketch. It will not be perfect but will have so much charm and feeling to it!