1. Don't skip it.
Unless you already have other plans that night that you absolutely cannot miss or change, show up to the office holiday party.
"You may not want to go," says Pachter, but it's important that you show your commitment to the company.
"Your absence will be noticed, and most likely, noted by your boss and other higher ups," she adds.
2. Don't dress inappropriately.
The party may not take place during traditional work hours — but that doesn't mean you should dress like you're going to a nightclub.
Wear work-appropriate clothing. Since it's a special occasion, it's fine to take it up one notch, but don't go over the top.
"It is a party, but your attire needs to be suitable for a business event, not a nightclub. Don’t wear anything that is too short, too tight, too low, or too anything," advises Pachter.
Also, if you normally wear a suit to work, don't show up to the office party in jeans and a T-shirt.
3. Don't fail to prepare your guest or significant other.
Many times significant others are included or you're allowed to bring a guest.
Let them know about appropriate dress and topics of conversation to stay away from, says Pachter. Also, make sure your guest follows all the rules. "His or her behavior will reflect on you."
4. Don't get drunk.
This is an important rule — and yet, so many people fail to follow it.
"You don't have to drink, but if you do, stay sober," says Pachter. "It's easy to do something outrageous when you have had too much to drink."
She suggests setting a limit for yourself before going to the party, and sticking to it. "It is much easier to limit your intake that way," she says. "Or, order a drink you don't like and sip it slowly all night."
5. Don't look bored.
Watch your body language. Appearing bored or like you'd rather be anywhere else is just as bad as not showing up at all.
"Don’t frown, slouch, cross arms, or yawn. You never know who might be observing you," she says.
6. Don't be anti-social.
Even if you despise your coworkers (hopefully you don't — and if you do, it might be time to assess your situation), or if you're new and don't know many people, don't sit in a corner alone or keep your eyes glued to your phone the whole night.
"Schmooze," Pachter suggests. "Talk to people you know and don't know. The party is an opportunity to meet people. Don’t spend your time tweeting or texting. Make sure you mingle."
7. Don't gossip or bad mouth your colleagues.
When you do speak to colleagues, keep the conversation upbeat and positive. Complaining about the company or your boss will bring the mood down.
"Also avoid discussing sex, politics, or religion," says Pachter. And, perhaps most importantly, don't gossip about coworkers.
It's easy to do all of the above when you've been drinking — so be careful.
8. Don't go in without a plan.
A good way to avoid defaulting to gossip is having a "talking plan." As Voltaire said, "One always speaks badly when one has nothing to say.”
If you're hoping to chat with a new coworker, think of a few icebreaker questions you can ask.
Did you decide ahead of time not to drink? Know what you want to say when people ask you, "Why not?" Or, perhaps you're planning to chat with the CEO. Think of a few smart conversation starters.
"Don't just talk business. Be up-to-date on current events and happenings in your community. Read the newspaper, your online news sites, news magazines, company publications, and your professional journals," Pachter says.
9. Don't forget to eat.
Sometimes employees skip the food and head straight to the bar because they're excited to drink with their colleagues, or they assume the catered hors d'oeuvres aren't worth the calories.
If you do decide to drink alcohol — even if you limit yourself to one or two glasses of wine — it's very important that you eat something.
10. Don't flirt.
This is not the time to hit on your boss, or his spouse.
Sometimes liquid courage gets the best of us — so stay away from alcohol if you don't think you can control yourself while under the influence.
11. Don't post photos or comments that could get you in trouble.
Avoid posting negative comments to social media about how "lame" the party was, or how much the food "sucked." Also, do not post photos of your colleagues taking shots or engaging in other inappropriate behavior.