Equip the handguns to both Rebecca and Billy. Control Billy. When you see a zombie, shoot him until he falls, but do not kill him. Then, equip the pocket knife and kill the zombie with it. This will save about two to five bullets each time. There are two knife tactics you can use to safe ammunition for the Bosses. The first tactic is used fighting solo without the help of Billy or Rebecca; depending on whom you use. Make sure you keep about two steps away from the zombie and aim downward with your knife. Slice him once then he will make a failed attempt to lunge at you. Then, slice his feet again and he will fall down. Once down, do not knife him any more. Instead take about a step backward and wait for him to get up and repeat this process again. This tactic works if there are multiple zombies. Alternately, if there is only one zombie you move to behind the zombie's head when he is laying down. Then, knife his head and keep knifing him as he gets up. When done properly you will knife his feet twice and he will fall down again. This will allow a few extra shots in as you knife his head while he gets up. The second knife tactic is used fighting with a team. The person you control should be using a knife, and either Billy or Rebecca should be using a gun (and set on attack mode). Get in front of the one with the gun and knife the zombie's feet. As you knife the feet, your partner will shoot the head and the zombie will fall down. Then, go over and knife the zombie while he is on the ground. As he gets up keep knifing him and your partner's help will assist you in finishing him off properly.