Run a lime wedge around the outer rims of 2 rocks glasses. Dip the rim of the glasses in salt. Fill with ice and set aside
Combine the tequila, Cointreau, and lime juice in a shaker. Shake for to combine liquid. Pour over ice in glasses.
Tips and Substitutions
Make sure the limes you buy are bright green and heavy in your hand. Squeeze the lime between your thumb and fingers. If the lime gives a little, then it is ripe and should be juicy. A lime that doesn't give likely is not ripe and won't have a lot of juice.
If you want to cut the alcohol percentage down, substitute triple sec for the Cointreau. Triple sec has about have the alcohol as Cointreau.
To make a frozen margarita, place ¾ cup of crushed ice in a blender with the margarita mix and blend until frosty.
Substitute a coarse sugar instead of salt to rim the margarita glass.
Use a quart glass jar to mix the margarita in if you don't have a shaker. You will see I did this in my video to improvise as my cocktail shaker was packed away and I couldn't get to it!