Firstly take a cocktail glass, or margarita glass if you have one, run a wedge of lime around the rim and then quickly dip in to a saucer of salt.
I'm quite fond of the taste of limes so my margaritas tend to lean that way and be quite sharp. I like to keep things quite simple too, so I use equal parts tequila, lime juice and triple sec. If there's any lying around the house I'll add a dash of cointreau. Shake with ice and strain in to the prepared glass.
For a long time this was omy favourite drink but I moved on to discover daiquiris...