Place equal portions of brown sugar and white sugar on a small plate. Stir the two sugars together until uniformly combined.
Lightly moisten the outside edge of each serving glass with a small amount of water.
Press each dampened rim into the sugar blend, turning the glass several times as needed to create an even coating around the entire edge.
Fill a cocktail shaker with ice cubes.
Pour in 2 fl oz silver tequila, 2 fl oz apple cider, 2 fl oz cranberry juice, and 1 fl oz orange juice or Cointreau.
Secure the shaker firmly and shake thoroughly until the mixture is well combined and chilled.
Strain the margarita into the prepared sugar-rimmed glasses.
Serve with additional ice cubes if a colder cocktail is preferred.