Prepare your glass: If desired, run a lime wedge around the rim of your margarita glass or rocks glass. Dip the rim into a plate of coarse salt. Fill the glass with ice.
Combine ingredients: In a cocktail shaker, add the tequila, fresh lime juice, orange liqueur, and agave nectar (if using).
Shake well: Fill the cocktail shaker with ice. Secure the lid and shake vigorously for about 15-20 seconds until the shaker is well-chilled.
Strain and serve: Strain the mixture from the shaker into your prepared glass filled with ice. Garnish with a lime wedge. Cheers!