Allow us to introduce you to the short sleeve printed shirt. Wearing one of these on a night out acts as a solid indicator that you've left the long-sleeved stuffiness of Christmas and New Year behind you, and that you're ready to embrace Spring in style.
Of course, the short sleeve's USP is its versatility, which means you'll probably smash it however you wear it. It looks good with chinos or a pair of skinny jeans, but can be sharpened up with a quick fastening of the top button and the addition of smart trousers (and a pair of suede loafers).
Oh, and if you're unconvinced about wearing one in January, naturally, there's the option of pulling on, say, a bomber jacket overtop.