Don't check-in on Foursquare all the time, everywhere you go:

• Your boss will realize that you're late to work every morning because you're out drinking until late every night.
• You'll slip up and check-in somewhere when you're supposed to be somewhere else.
• You'll annoy the hell out of co-workers, who don't give a damn that you're now the mayor of your dry cleaners.

Don't post every single picture from last night's party:

• Your co-workers will spot that unfortunate nipple-slip that your weary eyes glossed over.
• You may not mind, but the co-workers you're partying with might want to keep their social life separate from their work life.
• You never know how a party picture can come back to getcha.

Don't click links on Twitter if you're unsure what they link to:

• Sometimes NSFW isn't tagged NSFW.
• It might be an embarrassingly loud music video or audio clip.
• It might be anything you don't want popping up on your work computer!