For what it's worth these are my top ten tips in no particular order of priority
1) Use a reputable breeder and check out the conditions first. How healthy do the chickens look? Get point of lay hens and at least three. Hens are flock creatures and do not do well on their own.
2) Allow plenty of space. You need a minimum of 2 sq metres per bird and that does not include feeders drinkers and coop etc.
3) Be prepared to want to increase your flock. Chicken keeping can be addictive!
4) Fox proof your area - use weld mesh rather than chicken wire (foxes can chew through chicken wire) and possibly electric net fencing.
5) Little visitors! Use Flubenvet for internal parasites and Frontline kitten strength for external parasites.
6) Redmite. These little ***ers lurk in the cracks and crevices of wooden coops and drop down onto the hens at night to drink their blood. Use a cleaner like Poultry Shield, a disinfectant like Ficam W or Stalosan F. Make a slurry of diatomaceous earth powder mixed with poultry shield or detergent and water and paint into the cracks and crevices, not forgetting the perch ends.
7) Feeding - use layers pellets and give a small treat at about tea time such as mixed corn. If you have dark green veg leaves they are very good. Make sure you hens have some access to greens. Have grit and crushed oyster shell in separate containers available at all times. Have a good drinker with fresh water daily available. Food and drink should be kept outside the coop in the enclosure. The food should be under some kind of shelter so it does not get wet and remove it to somewhere rat-proof at night.
Bullying - There is always a certain amount of jostling for position until the pecking order is established. This doesn't usually draw blood but it is a good idea to have Purple Spray (yes it is called that though it is actually gentian violet) ready in case there are any raw red patches or blood. The spray disguises the colour so that hens don't peck at it.
9) Identify a local chicken friendly vet. Not all vets are, and some will even refuse to treat chickens. Keep the contact ready just in case.
10) Get a comfortable seat or bench to sit on so you can watch your hens. You will find that they can become addictive!