Before you even boil water, check the bag. Are they raw or pre-cooked? Raw frozen shrimp are the ones you want for boiling—they’ll transform from grayish to bright orange-pink. Pre-cooked shrimp are already done, so boiling them just turns them into rubbery little erasers. Avoid that tragedy.
Also, look for easy-peel or deveined shrimp. Nobody wants to spend ten minutes fiddling with a tiny vein while their water boils away. Trust me, you’ve got better things to do—like deciding what sauce to dunk them in.