Could anyone give me some advice on running the game outside of night city?

I got the game book a few months ago and its been sitting on my shelf. I decided to finally take a look at it and I'm pretty drawn in. I've been wanting to get out of the fantasy genre for a while. I'm not super versed on the gameplay but I'm learning. I noticed the game has a premade setting called Night City. It sounds cool, but I work better when I use NPC's and names I'm familiar with. I guess I've been doing fantasy too long and I'm having trouble coming up with Cyberpunk ideas. I COULD use night city, but I'd have to learn NPC's and locations and I'm worried any of my more learned players would be like "That NPC wouldn't do that! He's a family man not a cold blooded murderer!".

Could anyone give me some advice or examples of how you build your homebrew worlds? Maybe some unique locations or people that might be interesting?