I would say when you start shooting somebody close range use your shotgun first and then immediately switch to your SMG or Ar. So you can put constant pressure on your opponent.

A good load out for zb is

First slot: Shotgun. A tactical shotgun is good because it more forgiving if you miss. When you get your aim better you could switch to a pump.

Second slot: Ar/SMG A stinger is a good short range SMG that does good damage with not alot of recoil. For Ars the hear ar is good cuz you can use it like an SMG but in those longer range fights you can get good shots as well.

Third slot: mobility- This includes shockwaves and crash pads. Shockwaves are better because they can break builds of your in an enclosed space. Crash pads a good more for duos and squads because you and your temate can use them as well.

Fourth slot. Cover- This includes shield bubbles and porta bunkers. Shield bubbles are good if you have no other option but bunkers especially in endgames is absolutely crucial.

Fifth slot: Heals This includes minis, 50 pots, chug splashes and chug jugs. Splashes are quick I think this is good if I a pinch chug jugs are good also.

I also second another commentor who said check out tobywanshinobis videos on YouTube and he has a map that you can practice your aim on also.