It's a tiny, but simple thing to prevent future "oopsies." Write down what works, and what doesn't, at your parties.
I started keeping a Host's Journal about three years ago after serving a wine that, once I tasted it, I recalled I said I'd never buy it again. Mental notes are unreliable, but the written word makes things stick. So get yourself a small notebook (I chose an especially festive one), keep it in the kitchen and jot down tips, tricks, what works, and what doesn't.
An address book is especially expedient, allowing you to easily categorize food and drink alphabetically-- "W" for "Wines" and "B" for "Beers." Before your next party, review your notes to see which libations to buy -- and which to skip.