To make the rimming sugar, combine sugar and lemon zest in a small bowl. Stir to combine. Add to a shallow bowl or small plate.
To make the rimming salt, combine salt and lemon zest in a small bowl. Stir to combine. Add to a shallow bowl or small plate.
Rub the rim of a cocktail glass with a wedge of lemon to wet it. Swirl the rim through a pile of lemon rimming sugar or lemon rimming salt.
To make the cocktail, add lemon juice, tequila, agave and bitters to an ice-filled cocktail shaker. Shake well for 15 seconds.
Add ice to your rimmed glasses. Strain the margarita into the glasses, dividing the cocktail evenly. Serve.