Into a cocktail shaker, add ice, 2 parts whiskey, 1 part sweet vermouth, and a dash or two of bitters, such as angostura. The whiskey and vermouth are up to you, try picking some with complementary flavors or flavors that just taste good to you.
Rub an orange peel around the inside of your desired glass, add some ice, shake the shaker, and strain into said glass. Garnish with a maraschino cherry and enjoy!