WEll, let's see.....
Coop and run should be predator proof. Run should have a top.
Coop should be draft free and always dry.
Coop needs roosting bars at the appropriate height and size and nesting boxes
Area of shade is essential, also area for dust bathing and supervised free range time.
Tall enough for you to stand up
Easy clean and maintenance
Extra waterers, both inside and outside run
Build as large as you can with windows that can be opened in summer and closed in winter
It is so tempting to have more chickens that your current space allows. Your birds will be happier, live longer, produce more eggs, be healthier if they are not overcrowded. I think this is really important.
And last, every coop needs a sensible human to lock them in every night, keep the water clean and the food fresh, never let anyone chase them, give them love and treats and a safe place to live. The rewards are tremendous. Hope this is helpful.