There are two ways to cook squid: very fast or very slow. Two minutes or three hours -- anything in between, you may as well shit in your hat.
Slow, above: braised squid.
I cooked garlic and chopped hot peppers in oil for a minute or two, added about equal amounts of red wine and Trader Joe's marinara sauce (mostly tomato and basil), and chopped squid (including tentacles), and barely simmered it for three hours. The squid goes from cooked and edible to rubbery like a finger puppet to tender but a little toothsome. Serve over pasta. Goat butter garlic bread would've been awesome alongside.
Fast, not pictured because a Picasa update ate the photo: Buffalo squid.
Slice squid bodies into rings. Spread out on a kitchen towel to blot the surface moisture away. Dredge with a combination of flour, self-rising flour, and Old Bay. Heat oil to pretty hot, so that the temp doesn't drop much when you drop the squid pieces in, and fry until just cooked -- about a minute and a half, two minutes. Drain, toss with Buffalo wing sauce, serve with ranch and celery sticks.