The trick is front-loading your night so you're done celebrating by like midnight or just after, then actually getting to bed instead of riding the party till 3am. Eat something substantial before you start drinking, stay hydrated throughout, and if you're going out, set a hard cutoff time and stick to it - your future self on January 1st will thank you. If you want to still have fun, focus on quality time with people you actually like rather than trying to outlast everyone else, which honestly makes the whole thing less enjoyable anyway. And yeah, get some sleep before the 1st, not just after - going to bed at a reasonable hour on the 30th helps way more than people think.