Most people prefer to deal with the catch as soon as practical. The first step is to kill the crayfish humanely by drowning it in a bin of cold fresh water. Placing a live crayfish directly into boiling water will result in the legs falling off more easily. 
If you intend ‘cooking’ the crayfish immediately by boiling it, there are some simple steps to take to bring the best out of your catch. It is important to bring the water to a rolling boil before placing the crayfish in it. Do not overload the pot as it takes too long to bring it back on the boil; keeping the lid on the pot helps with this. Time the crayfish once the water starts to boil. The ‘just legal’ crayfish should be boiled for no longer than six minutes, and up to 12 minutes for ‘monster’ four-kilo-plus crayfish.
Once time is up take the crayfish out of the pot and place in a tub of cold water to halt the cooking process, then remove and leave to drain. A good way to do this is to hook the curled-up tails on the rim of a bucket.
Once cooled and the flesh set, the tail can be twisted free of the body and sliced lengthwise with a sharp, sturdy knife to split it. The alimentary canal will be exposed and this should be removed. Similarly the body can be sliced lengthwise in two, exposing the ‘engine room’. The yellow ‘mustard’ can be removed and used to give flavour to any sauce.
To many people, sucking the sweet morsels out of the legs and body is every bit as good as the tail meat. Use a nutcracker or a purposebuilt lobster claw cracking tool to crack the shell.