When you decide to load up an zombies game, first things first.

Points:

Try to gather as many points as humanly possible and learn how to survive at least opening only one door, more can be opened depending on the map. For example what i like to do, is hold out on first and second room on five until round 8-9, round 7 is maxinum round that i can do in the first room on co-op, and round 5 or so on solo. If you get to power before round 8 buy the bowie knife, it can get you crazy amount of points. I usually prefer to get at least 8000-10000 points on co-op and on solo at least 5000-6000 points.

Training.

Learn training in tight areas, such as in war room of five (without opening two gates on left and right) Try to learn how to use mustang & sally's on every map that also does not contain PhD perk. What i used to learn it, i just fired on one of them and got zombies down easily. Remember using mustang & sally's on a map without jug, needs more skill and is it not advised to be used as an safe gun as an better wonder weapon, like thundergun or wave gun. Also if you struggle to learn it, play bo2 nuketown because the map teaches you how to be careful when training around in those tight spaces. But as of now with the recent security issues with bo2 on Steam, i highly advise not to play it.
But the equilewant of bo1 is five, because of the higher skill set and it offer an unforgiving map for them who dont how to play, but it is awesome to learn training, due to its tight and compact map design. For a bit of challenge boost you can go to the "pig room" and train your zombies there, but it is proven to be way harder than training on war room.

Perks:

Explaining for perks.
Honestly for most of maps you really need Juggernog and quick revive for solo (optional). Reason why i choose two, is that yes you can have four perks at the same time, but if you are playing ascension, monkeys take your perks easily and defending two perks as an single soldier on the battlefield is easier.
On co-op you take variety of perks on your disposal, because there is more zombies so you need more of that speed cola and mule kick, if you love using 3 weapons at the same time. And if your team contains a bunch of mates that need reviving, quick revive comes really handy at those situations. PhD is great option for maps that contain them, for easier gameplay with explosives. Stamin-up is really useful because you get a 7% speed boost and you go faster for longer times. Deadshot is not really useful, unless you play on controller, due to it giving head level aim for controller and smaller crosshairs. Douple Tap increases your fire rate by 33%, it can proven to be really useful for some slow firing weapons like, HK21 for example. Spped cola gives you faster reload time of weapons, which you should guess by the name of it. Mule kick gives access to carry an extra weapon at your disposal, but you lose it when you go down.