My dad does it this way and always comes out a winner.
Below is my dad's text messaged reply to me when I requested his in-it-to-win-it margarita recipe. I used it to complement Taco Night last Thursday night at the beach when it was our turn to cook for the whole assembled gang of more than 20 relatives. By the way...Taco Night also always comes out a winner.
"Fill blender 3/4 full of ice cubes.
1/2 container of frozen limeade (6 oz.)
6-12 oz of water
6 jiggers* of tequila
3 jiggers* of triple sec
Blend on high speed.
Salt rims of glass.
Add fresh lime slice.
Pour and enjoy.
No driving if drinking."
Gotta love dads.
*a jigger is the precise 1.5 oz measure of a shot