One thing that actually makes staying sober harder is announcing it loudly - people feel obligated to police you or they push drinks on you out of habit. Instead, just tell your close friends quietly what's up, and then order a fancy nonalcoholic drink at the bar that looks substantial, like a virgin mojito or something with bitters and club soda. Nobody questions what's in a drink that looks legit, and you're not nursing plain water all night which gets boring fast. The other big thing is having a specific reason to stay sharp - maybe you want to actually talk to someone, or you're driving, or you just want to feel good the next day. Having that anchor makes the whole thing way easier than just white-knuckling through willpower.