This might be an ongoing series. Feel free to chime in with additions.
Don't be the guy who has work killed by the creative director for one reason or another, then walks the halls explaining to anyone who will listen why you disagree with said creative director, why killing your work was a mistake, or why your creative director just isn't getting the humor of your work. You may find someone who agrees with you, but you shouldn't need sympathy to do your job. Having work killed is part of the business. Learn to live with it. Let it go. Move on. There are plenty of fun ways to waste your time in an agency that don't also involve wasting other people's time.
