If you want a salted rim, you'll do this first. Run a lime wedge around the rim of your glass to moisten it, then dip the rim of the glass into a shallow dish of salt.
Squeeze fresh limes to make lime juice.
Muddle the fresh raspberries in the cocktail shaker using a muddler or the back of a spoon.
Add the tequila, lime juice, orange liquor, and agave syrup to the shaker.
Shake the ingredients together with ice for about 20 seconds.
Strain the mixture into a prepared glass filled with a large ice cube. The raspberry seeds can get stuck, so you must shake the shaker to get things moving.
Garnish with additional fresh raspberries or lime wedges, if desired.
Notes
Add more or less tequila or sweetener based on your preference. Swap out agave with simple syrup. Shake the cocktail with ice for 20 seconds to dilute it.