1) You don't measure your pours
You've got this. You finished watching Cocktail
for the 18th time, loaded up an '80s playlist with Starship's Wild Again
appearing no fewer than four times, and are ready to start slinging drinks to a mob of attractive women throwing money at you. But then reality kicks in and you realize you're the only one who likes Starship, the "women" are just your friend Todd, and your cocktails taste like the runoff from a Long Island Iced Tea factory because you think you can just eyeball everything. With something as delicate as a cocktail, upsetting the balance even an iota can throw off the entire flavor profile, so make like a pro and use a jigger
to actually measure out your ingredients.