Watching a master bartender, you might think they have a Wikipedia of recipes in their brain. The truth is, the list is much shorter. Most cocktails come down to a simple ratio, explains Charlotte Voisey, director of brand advocacy at William Grant & Sons. Learn a formula, then switch in your favorite flavors, what’s in season, or ingredients that will match the occasion, and you’ve got a great drink, she says. Here are four classic recipes, with a few suggested twists to get you started.