Temple of the Seven Golden Camels: Carrying a Sketchbook, part one
2 saves http://sevencamels.blogspot.ca/2007/03/carrying-sketchbook-part-one.html
"Any real sketchbook is full of misfires, false starts and stumbles, with a few successes sprinkled here and there. If you were capable of doing a perfect drawing every time, you wouldn't need to carry a sketchbook! But the quickest way to learn how to do perfect drawings is to do a lot of crappy ones first...and learn from them.
So don't view your sketchbook as a place for perfect drawings. That's not what it's for. It's for learning. If you pressure yourself to do perfect drawings you'll never carry a sketchbook. That's too much pressure and it takes all the fun out of sketching.
Don't focus on how good or bad your sketches are, instead focus on doing your best to capture what you see and learn from it. "