Don't let your mind wander -- it's too little to be let out alone.
Don't look back, the lemmings are gaining on you.
Don't put off for tomorrow what you can do today, because if you enjoy it today you can do it again tomorrow.
"Don't say yes until I finish talking." -- Darryl F. Zanuck
Don't steal; thou'lt never thus compete successfully in business. Cheat. -- Ambrose Bierce
Don't suspect your friends -- turn them in! -- "Brazil"
Don't take life so serious, son, it ain't nohow permanent. -- Walt Kelly
Don't take life too seriously -- you'll never get out of it alive.
Don't tell any big lies today. Small ones can be just as effective.
"Don't tell me I'm burning the candle at both ends -- tell me where to get more wax!!"