These questions come up a lot from people who are just beginning to explore the world of cocktails and mixology. "What does muddling mean?" "How do I muddle?" "Can I muddle too much?"
The answers are easy. When you muddle an ingredient for a cocktail, you're simply breaking it down to allow the natural flavors to be released into the drink. By using a little force and a slight turn of the wrist, you press the ingredient enough to expel the essence, juice, and/or oils.
It's possible to muddle too much with some ingredients, just like it's possible to oversalt or overcook a meal. But it's largely up to personal taste. For example, some mixologists believe that mint should be gently pressed so as not to release unwanted oils. I want everything mint has to offer and will muddle mint until it's unrecognizable. But when it comes to thyme, I'm gentler so as not to get too much of a twiggy taste from the stem.
The key is to practice. The more you muddle a variety of ingredients, the more you'll develop the technique.
Watch this 6-second Vine video of muddling: https://vine.co/v/hhZt7pYPMpJ/embed