I must be on a seafood kick lately, this makes 3 posts in a row! Maybe my body's craving mercury. Heh.
I decided one day that I wanted steamed clams and mussels. So off to the market, $5/lb, I bought a bunch of each. All my clams behaved well, but I had 1 cracked mussel and 1 that didn't close when I tapped him. Those get tossed. Unless you like feeling like you're going to die.
In a large pot, melt butter, add wine, lemon juice, smashed garlic, salt, pepper (black or red), maybe a bay leaf. You could also replace the wine with beer if you want. Bring it all to a boil, dump in your crustaceans, cover, let steam for 3-5 minutes, uncover, stir, let steam some more. They're done when they're opened. (And by now you all know to toss any that don't open.)
Make sure you have some good crusty bread to dip into the "broth". And a lot of napkins.