If you take on Nemesis the best strategy is to run by his right side. He is a lefty so he will always try to grab or pummel you into submision with his left hand. Once you're a little ways behind him (make sure it's not too far otherwise he will run at you, then your in trouble) take a shot and run by him again. Keep doing this until he falls over. He will get back up so continue until you see the purple blood from his body. If your playing HARD mode make sure you pick up the item.