1. Don fall in love with your colleague.
Your boss will think you are doing other things when you are talking about business with your boyfriend.

2. Don't dress yourself smarter than your boss.
Maybe your boss has a bad taste, but you should never show your name brand dresses to him/her. Especially when your boss is a woman, you should try your best to concentrate your attention to your work, not your dress.

3. Don't make friends with your colleagues.
You only consider them as the strangers who you work with. Telling your private affairs to them is like burying a bomb around you.

4. Don't say dirty jokes to your colleagues.
This is nothing to do with humor. Though maybe they laugh when you say those jokes, they will have a bad impression on you.

5. Don't flatter your boss obviously unless he is really an idiot.

6. Don't forget to power off your mobile phone in the office. That will annoy your boss or colleagues, especially during the meeting.