It has a dirt/ sand floor.
I know clear the weeds and check the fencing. Thats a no brainer. It has a hot wire on it too. We have predators.
My concern is disease.
I would look up how to clean a coop from mites, because mites can be some of the toughest buggers to get rid of, I would bet that doing a mite sanitation would clean it of just about anything else. I've heard of people using a diluted bleach solution or dish soap and water. Some people use oils and Diatomaceous Earth (although now we're getting pretty mite specific). Since it's been so long since there were birds in there last, I would personally just do the Dawn dish soap and water spray.
Hope this helps,
I would bleach it good, let it dry to kill all disease, and to kill any mites sprinkle a box of borax all over the floor, roosts, nesting boxes etc and let sit for a couple of days.
I use borax every time i clean my coop in this way, but just a little mixed in with the shavings and it keeps a coop lice and mite free.
I had a lice outbreak, so I sprayed my coop down with permethrin spray. It's so easy to use and pretty cheap too. You can keep it on hand in case of a lice or mite outbreak, but fingers crossed that won't happen! Just be sure it is all aired out if you use bleach, as it can cause respiratory issues in your chickens. If you have the time though, a good bleach will probably take care of all of things all at once! Good luck!