These tips came to mind as a result of a recent ride I took on an elevator downtown...
Don't fling your bag, leg, or other appendage into the tiny crack of an elevator door that is nearly closed. This type of move can be perceived as either forcefulness or desperation - neither of which is professional or becoming. There will be another elevator - show some class, patience, and good sense and wait for it.
Don't talk on your cell phone. You are very likely speaking much louder than you think you are. Elevators are small, closed in spaces and the sound reverberates. It is uncomfortable for those around you who neither care nor are impressed with your side of the conversation.
Don't pretend to be polite and let me go ahead of you out the elevator door only to walk one-half step behind me down the narrow hall, breathing loudly, banging your briefcase, and otherwise letting me know that you are in a hurry. If you really are in such a rush, then move to the front of the elevator as it is landing, then bolt off and stride away as soon as the doors open. I appreciate the latter approach because it is honest. Your passive-aggressive attempt at politeness that you don't really feel is just plain annoying.
Thanks, and have a nice day!