I find it best to rip their backs off n wash out guts etc gently with running water. So not to marinate them in their own filth. Also I cut gills n eyes off. Boil water (sea water), turn on low simmer and simmer for 7 to 8 mins max. Keep in fridge covered for no longer than 2 days otherwise they become dry n very low tasting also. Damn I love crab n it has been a great crab season. Enjoy mate.