Squid is super easy too cook, and like sandman said, the best advice is to not overcook- 30 seconds to a minute in hot oil is all you need. Unless you like rubber
I like to cut them into squares, then cross-hatch with a sharp knife so the cuts go about 1/2 way through the meat. When stir fried it's really tender.
Wish we got the longfins up here like you guys down south do!!