Being nice to everyone

Being smart at work:

With the experience that I have been in industry, I am sort of learning how to be nice. First important thing is leave out all your personal problems, when you are work place. Even if you have some problems, don't show them up on anyone. Control your emotions and feelings.

Being smart to your manager:
When manager assigns you more work, don't ever say on his face "I won't do this". May be try to convince him showing how you are overloaded with other works. When you have not completed in a stipulated time because of some valid reason, tell him that "It is almost done, but few issues in doing blah blah".