Fill a tall glass with ice and leave to one side (don't bother with a martini glass unless you're trying to impress the ladies).
Fill your Boston shaker with ice. Add the Gin, the Orange liquer, the (freshly squeezed) lime juice, and then top with the Cranberry juice. Close the shaker and shake your thang!
Poor the mix into your tall glass. Take your slice of orange peel and heat over a lighter flame just a little(don't use matches - stinky sulphur!). Run the peel all the way around the lip of the glass and drop it into the drink as a garnish.
Sit back and enjoy a great alternative to a regular Cosmopolitan.