A great tip was passed to me by a writer who also has over 30 years experience as an editor.
He noted that, when proofing, you can never relax your vigilance. "I've noticed that when I find a mistake on a line, I am very apt to miss the next mistake on that line. The reason is simple: I'm so busy basking in pride at my cleverness in having caught that first mistake, that I miss the second. And mistakes do tend to cluster - perhaps because the original writer was tired or distracted at that particular point. You can't let your guard down!"
