Get a good gun with good reloading and fire rate. enter a building near ravenwall. (apartments are highly recommended) . walk around till u see a green zombie, fight it, dun run away cuz the rewards are good. note that there will be little space for manuvering, so you should kill of any zombies that come into the room. because it took me about 300 rounds of a p90 to kill it, along with the other zombies. loot the zombie after that, on my first try i got lvl 15 armor. but u can melee it instead if u see it on a street.