Always buy chicks don't buy chickens that are a year old or older. When I did that the older birds never got over the stress of the new environment.
Raccoons are evil and they will kill your favourite chickens first
don't have favourites
don't name them (raccoons kill all the ones with names first)
a cat can kill a chicken and eat it
mink can sneak in and kill everything
To keep my chickens alive I have built a fly in coop that a cat, mink, and RACCOON can not climb into, it's on stilts (which also keeps it dry in winter) and the chickens fly in at night and fly out in the morning, but I still close the door. The best defense against raccoons is a Great Pyrenees dog or two in the yard, or a pig - one of the small breeds.
Heavy breed chickens are the best defense against birds of prey because they are too heavy for the birds to lift off the ground.
Broody hens sometimes kill their chicks, don't count them before they are 3 months old because mericks disease
feed the raccoons and they wont eat your chickens
If I had known all this I would still have all my favourite chickens...