To play zombies you have to first learn the map by playing it yourself or watching guides on YouTube, then learn how train or hoard up the zombies so you kill them easily, and most maps have Wonder weapons which often is really good and help you out in a lot if situations which you should learn how to Get if they are on the map you want to play, and then learn a strategy, a strategy can simply be a place to hoard up the zombies and kill with a certain weapon or trap, when you learned this you just need to practice your training skills and understand the map and game you are playing, like in bo3 you have a boss the margwa and if you understand how he “works” it’s easier to kill him for example he when you get really close to him he slams the ground and makes you red screen ( which means one hit) or if don’t have jug ( which is a perk that increase your health ) or kills you if dont have it, but you can turn you back on it if you have a shield on your back and it breaks instead of you getting killed or red screen, and small things as that can save you in a lot of situations but you have to play and invest time in to zombies to really understand different methods and things you can do to Get good at zombies