What to do with medical bills?

I am in the process of paying all my debt off from money I got as an inheritence. My question is, for the bills that are in collections do I try to get a pfd? We have 2 that are just under 300 dollars and a couple other small ones. And for the bills that are not in collections yet, do I need to worry about how I pay them? If they aren't on my credit report now, will they stay off as long as I pay them in full? As of right now my credit score is very low and I am just trying to figure out the best way to start repairing it.