7. Don't be that guy; don't drink so much that you pass out.
You may be sensing a theme here. All these things you shouldn't do are related to not being embarrassed when you eventually go back to work with these people: getting too drunk, puking, then passing out is near the top of the embarrassing-as-shit scale. Sip, don't gulp, damn it -- drink to have fun, not get smashed. Remember, these aren't your college buddies here; these are your coworkers -- you never know who might take joy in posting you laying in your own puke on Facebook.
6. Don't bring your friend who is always "that guy" to the party.
If there is any question as to whether your friend is capable of not embarrassing you for three hours, leave him at home; this is your job. The only thing tougher than keeping yourself in check at a holiday party is babysitting your drunken, nothing-to-lose friend at one; go solo, or bring a date. If you're even wondering, then yes, he is that guy.
5. Under no circumstances are you to give an inappropriate "Secret Santa" gift.
Don't be a jackass. Not everyone at your holiday party is going to think wrapping a six-foot blowup doll with your face attached to it is hilarious; don't make everyone uncomfortable. The last thing you need is dirty "creeper" looks the rest of the year, so don't put that on yourself. Secret Santa is easy; just get a Starbucks gift certificate and be done with it -- don't try to be creative for under $20.
4. No talk about religion or politics; this isn't the time or the place.
You're going to find yourself standing in semicircles discussing who-knows-what, but under no circumstances should you ever bring up religion or politics; it just never ends well, and it puts a damper on things. This is a party for fun and celebration; nobody wants to know how you would conquer ISIS or why you think Obama has failed us right now. Keep it light: Bring up how ridiculous Miley Cryus looked at Art Basel or something else you can all laugh about.