Hi Keith.
Here's the best tip you will ever get.
Clean them first!
Makes an amazing difference to quality of body meat.
Once cleaned. Big Pot. just an inch of 2 of water and well fitted lid. Plenty of salt (or even better clean sea water. Bring to the boil. Put in crabs. Bring back to the boil and then boil/steam with lid on for 13 to 15 minutes (depending on the size of the crabs.
Fresh bread/cold beer =
PS : I cook and sell about 200 on a good week amongst the 2 tonne of fish I use a month inmy business and grew up on them as a kid. CLEAN THEM FIRST.
KC