1. It must have the right look
First, and most importantly, you have to look cool drinking your drink. I am not joking. A ginormous blueberry margarita may taste delicious, but nobody wants to be seen walking around with a glass of something that looks like it was bought from a 7-11 at 3 in the morning.
A drink is an accessory just like a necklace or your mustache: It has to fit with and enhance your look. Is your look more Champagne flute or rocks glass? Coupe or ancient Viking goblet? Starting with glassware and working backwards will help narrow your options. (For example, if you are going with Viking goblet, the only appropriate drink for that is THE BLOOD OF YOUR ENEMIES.)
[Photo via @jiggeristanbul]