The first do is obvious and important: Do attend the party. While obviously not mandatory, turning down an invite for anything but sickness or a death in the family will be construed as anti-social behavior.

Do understand the conventions of an exchange of white elephant gifts and Secret Santa. For both, participants (anonymously) bring a present of an agreed upon value. Each person draws a number which determines the order in which they choose a gift. Each person also has an option to steal someone else's gift. In the version involving white elephant gifts, the rules are the same, except the gifts are intentionally peculiar or humorous.

Don't get sloshed. Drink in moderation. Things done while drink are typically don'ts. For example: Don't use the opportunity to vent about the workplace. Don't gossip. Don't flirt or make lewd jokes or advances. Don't gush about your personal life. Basically, don't make a fool of yourself. Although the atmosphere is admittedly more relaxed than during the workday, your colleagues and superiors will remember anything odd or offensive you did on Monday morning, and that may color their impression of you.

Do take the opportunity to mingle with co-workers that you don't usually have contact with. This can be a simple reaching out to someone you see everyday but haven't really had a chance to get to know, or it can be downright schmoozing to the boss. Show your human side and impress people and you are more likely to get favors or a leg up.

In general, corporate holiday parties are an opportunity to interact with your colleagues in ways that the normal workday doesn't afford. However, that does not mean that the event is a Twelfth Night-esque where all decorum goes out the window. Company holiday parties are still subject to office politics as well as normal strictly social holiday party etiquette. Do have a good time, but don't wreck your career.