Man shaking a cocktail over his shoulder.
The Wrong Way To Shake A Cocktail, And How To Correct Yourself

To avoid overshaking your cocktails, use the over-the-shoulder method and a slow 10 count. At 15 seconds, you've probably shaken too much.

It’s best to shake cocktails horizontally. The ice won't break down efficiently using a vertical shaking motion, as it won't be exposed to as much surface area in the shaker.

Professional bartenders prefer the Boston shaker with a pint glass and Hawthorne strainer set-up because it's faster. Just make sure to keep the glass on top to avoid spillage.

When you go to break the seal, pop the shaker with the palm of your hand above the seal line. Trying to pop the seal on a hard surface will most likely shatter the glass.