Though a bit more obscure, the Emerson is actually quite easy to remember if you associate it with two of the better known gin classics. The Martinez is disputably the predecessor to the Gin Martini and can be thought of as a 'sweet gin martini.' Take the Martinez combination of gin, sweet vermouth, and maraschino and add lemon juice to create an Emerson. There are a few more tweaks to the ratio, but you will at least remember the ingredients.
As one reviewer said, this cocktail can also be likened to the Aviation Cocktail and you may enjoy it with a dash or two of bitters.