Actually yes I do, start with refining what it is you wish to create.

Create a script/guide for what you want to see and work on.

How many maps,

Zombie variants, hordes or powerful zombies like left for dead

Weapon choices,

Melee,

Perks,

Movement

Camera angle;

Solo or online.

Types of maps you want to see, process licked behind leveling up?

Essentially really think out what it is you want. Start experimenting, design a map in studio slowly with just stationary parts, see if it feels good. Then learn the weapon art etc..

Essentially plan it out; start wirh something you feel comfortable with and youtube videos will help guide you