I am not a cook, never have been, never will be. I know almost nothing about cooking and usually do not have enough patience to cook anything without walking away and letting it burn. Having said that, I have cooked a quite a few crawdads in my time.
There are numerous ways to cook them up. I won't even try any recipies due to reasons given above. I cook them much like a bunch of tiny lobsters, since this is what they basically are.
You need a lot of them to make a decent meal, and they are a lot of trouble. Bring a large pot of water to a boil with spices of your choice to add flavor. I personally like using pickeling spices with a few cloves added in, personal tastes differ. Drop the buggars in and let them cook to a nice bright orange (approx 7 min.). Take them out and let them cool under cold water, or eat them hot. Just remember that the boiling water makes them really hot on the inside.
If the ones you have gotten are large, the claws are excellant. If they are small they are just frustrating to try to get anything out of. The tail is the best part. Break off the tail above the ridges, you'll see, and grab the middle fan thing, don't have a clue what it is really called, on the end of the tail. If you give this a 90 degree twist and gently pull, the string of black stuff, enough said, will come right out. You can dip them in butter, sauce or whatever, or eat them plain. Mmmmmmmmmmmmmm......
Hint about catching them, take a piece of fish or some other meat with you and leave it, or them if you have more than one, and go about your dive. Very soon they will be all over it and you can catch them. Remember that they move backwards so this is the direction that you want to block.
I'm sure others here have other ways to get and prepare them, this is just mine. Good luck and happy hunting!
Later, Hawk.