A traditional Cocktail glass has a cone shaped bowl on a stem, supported by a flat base. This style of cocktail glass is often refered to as a Martini glass. The stem allows the drinker to hold the glass without touching the bowl and warming the drink.
For many tequila and fruit based cocktails you will want a Margarita glass. Normally rimmed with salt or sugar these are the ideal glasses for your tequila cocktails.