Wilko J. Hollemans PA3BWK - "Practice SENDING very fast but ACCURATELY - this in itself will improve your ability to copy fast code. Also use a tape-recorder to tape your sending, and then try copying it a week or so later.
One final tip - throw the pencil away, copy in your head! Try to run at higher speed than you are used to do."
"When learning to copy higher speeds, practice writing down the character only after hearing the following character. Once this is practiced a bit, hold off writing down the character until hearing the second character afterwards"