smile alot.
DL5treez had some good points. So did Hohn.
In general - discuss issues based upon facts. Like ^^^^ said, go to them with solutions based upon facts rather than "I think" type of ideas. Make charts and visual aids.
don't gossip. Listen to gossip and use it to your advantage but don't spread it. Don't complain about your boss/ bosses boss etc - the person you're talking to may be a mole, or a gossip hound that will spread it to the wrong person.
Do exactly what you're told, and do it well. Only vary from the plan after getting your idea approved.
Dress nice. Don't look like a slob. Get a haircut. Shave. Use Deodorant. Trim your nose/ear/neck/back hair. Easy on the cologne - light is OK, bathtime is a no no. Clean cut people get promotions.
don't spend too much time on the TDR while at work.
when dealing with female coworkers don't stare at their boobs/butts/etc. People notice that, even if the person you're looking at doesn't. It's considered a liability if you do - a lawsuit waiting to happen.