5. Don't dress like a clown
Displaying a touch of non-denominational holiday cheer casually projects confidence and personality, and provides an icebreaker for inevitably awkward interactions with any coworkers whose countries of origin you couldn’t find on a map. But cranking your sartorial splendor up to 11 will read as a desperate cry for attention, so maybe avoid having a gang of reindeer reenacting the Nativity all over your torso.
6. Don't try to be the guy who puts "Christ" in "Christmas"
You likely work with a mix of people of many creeds, colors, and denominations. Even more important than possibly offending them with your 10-minute screed about "Merry Christmas" vs. "Happy Holidays" is definitely embarrassing yourself with that speech. Nobody wants to hang with the dude who has extraordinarily strong opinions about, well, anything (unless it's Yu-Gi-Oh cards!), but especially not about a salutation used one month out of the year.