It's good to keep an eye on your girls to make sure they're in top physical condition. Healthy hens should be bright and spritely with their tail up and keeping active.
One way of telling how healthy your hens are is by their droppings. They should be firm and dark but 1 in every 10 droppings will take on the appearance of chip shop curry sauce. This is called caecal poo and is just an indication that the hens gut is having a good clear out. Loose looking droppings like diarrhea can sometimes be caused by the hens eating plenty of slugs and worms but it's best to keep an eye on them to make sure they're not poorly. Their vent (bum) should be clean and clear also.
Unless you have a young pullet your hens should have bright red combs which stand firm (unless they're of a particular breed). This indicates that the hen is in lay.
The chickens eyes should be clear and bright with no discharge. The same applies to the nostrils. For information on common ailments etc, click here.
The Right Way to Keep Chickens
by Virginia Shirt
Diatom - Effective treatment and prevention for Red Mite
When selecting eggs to hard boil, choose eggs which are over 3 days old to avoid the egg white clinging too much to the membrane (which can make peeling more tricky).