I don't think Schneier recommends a hint. That's only good if your password sucks to begin with.
And it's not the 'writing down' part that's a security risk, it's the 'storing in an insecure location' that is. Password in wallet, fine. Password post-it stuck to monitor, not fine.
"If you can't remember your passwords, write them down and put the paper in your wallet. But just write the sentence - or better yet - a hint that will help you remember your sentence. "
