Acquire your squid fresh. In preparation for battering and deep frying, be sure to remove the inedible innards. Just separate the legs from the body and you'll see a slimy bulb that shoots ink. Don't eat that part.
On this day, I ended up cutting out the squid body completely and just ate the legs.
Mix your batter. I put corn starch in this photo, but I ended up using tempura batter, which is actually what I'd recommend, especially if you prefer a Japanese flair to your calamari.
Batter up your calamari and deep fry them at around 325 degrees. They really shouldn't be in there for more than a minute. Perfectly-cooked calamari straddles a fine line between fishy-tasting (undercooked) and chewy (overcooked).
Enjoy.