I keep getting asked this lately so I thought I'd throw this up to explain it.

    I've been asked how I manage to get clean lines in my sketches or just in general. The answer really isn't an answer, it's a difference of approach. Using your wrist you can make small repeated lines in a sketch to outline the object you are drawing. This is often times very inaccurate and requires a lot of cleaning to remove those extra lines coming off the final line. However you can't exactly make long lines with your wrist without zooming out, but zooming out makes the accuracy of the line drop off.
    To fix this problem I raise my wrist off the tablet enough so that I can move the pen with my arm instead. This lets make make long strokes without zooming out and leaves behind far less extra bits that need cleaning up. It takes some getting used to, but this method is also far more precise and it makes curves much nicer looking. The only time I use my wrist is to make small strokes for small details.
    Another tip I can give is to OVERSHOOT your target endpoint for a line in some cases where you're drawing a specific shape or particularly long line. Doing this keeps the curve consistent and clean while remaining precise and on target. You can see that difference in the two boxes at the top.