A few years back I had scheduled a date a week in the future and wanted to look gorgeous to impress the dude. I discussed it with my friend Meg -- what to wear, do I get my hair cut, I needed new makeup -- and she stopped me.
"Honestly, the only thing you can do is drink a lot of water
and get a lot of sleep."
Her very wise point: you pretty much look like you look, even if you spackle on the make up and truss yourself up to the nines. Within an hour of leaving the house, all the artificiality starts to fall apart (if you're me, which I am, with limited patience or interest in checking my lipstick every 10 minutes or powdering my nose. This is not because I am not vain but because I am easily distracted.)
So if you have a big night coming: hydrate and sleep well the week before, then leave it to fate.