There are numerous ways to make a caipirinha, and that's before you start changing the spirit to make caipiroskas and caipiríssima (with either vodka or rum). Here is one of the most common methods but multiple adaptations could be made! Or get really radical - sakeirinha is made with sake and strawberries instead of limes.
Allow around one juicy lime, a good tablespoon of sugar and at least a double shot* of cachaša per glass.
*if your bottle has one of those filters in the neck then about 5 seconds will do.
Mash quartered limes in the bottom of each glassá - you can use either the end of a wooden spoon or a fancy lime masher.
Once you have released a decent amount of juice add the sugar and give it a good stir to allow it to startá dissolving.
Use a tea towel, the floor, and a rolling pin to crush some ice and fill each glass to the brim.
Finally pour the cachaša to fill all available voids and give a gentle stir.