Which glass should I use?
The cocktail world is a little less rigid than the wine world when it comes to glassware. While there is wide variation in size and shape (mostly designed to accommodate the portions and overall quantity), there are plenty of substitutes. Use what you have and make that drink!
A good rule of thumb is to mirror the size of the intended glass...so for a martini, use a small wine glass. For an Old Fashioned, use a small water or juice glass; a Bloody Mary use a large water glass.