Shaking is generally best with flavorful and/or thick mixers (fruit juices, simple syrup, egg/dairy, simple syrup, etc.) and stirring is best with cocktails using distilled spirits or light mixers. This is mostly because the thickness of the mixer determines the force necessary to combine it with the alcohol. For aesthetic purposes, shaking also tends to create a cloudy look which will turn more translucent once strained. Stirring, however, will give you a more precise amount of dilution. Stirring is also slightly "safer," as shaking can result in bruising the alcohol. Watch these 2 videos to learn more about the merits of shaking vs stirring and vice versa. http://how2heroes.com/videos/beverages/shaking-cocktails-the-perfect-margarita http://how2heroes.com/videos/beverages/perfect-gin-martini-stirred-not-shaken