Make sure you have as close to 1 sq foot of permanent ventilation in the coop as you can manage.
Secure all the openings in the coop with very well secured 1/2" hardware cloth.
Shoot for 1 linear foot of roost space per bird.
Install a 2' predator apron around the base of you coop/run setup.
If at all possible, install a solid roof on your run.
Try to give them 3.5-4 sq ft of floor space in the coop and another 15 sq ft of space in the run per bird.
If you have really nasty characters, consider running hot wires around your setup. They keep every manner of critter at bay.
