How to clean up a development process?

Hello!
I have a simple question, how do you guys work on you game? I mean, for example, you need a map, two characters (player can select one of them), some items like weapons etc.

How to work clean?

Do you create a new project for each, like project for the landscape, project for characters, project for items and then just migrate all into one? Or are you working in one project?

Also, do you have some tips, for beginner who is working without a team, but not like look for a good team :)?

Thank you in advance!

Here is the normal pipeline for Indie developers “not talking about AAA games”

  1. Get ur idea, sketch it on paper even
    just write up whats in ur mind.
  2. Sketch out what assets u need for this idea roughly, characters, weapons, one simple map, props for prototyping .
  3. Start Generate ur assests using any software , or buying them, or even hire someone to do it for u.
  4. after that, import ur assets in ur engine and start the first phase , just implement one simple level that apply ur idea.
  5. once the idea is clear, keep it up nerfeing ur idea and gameplay.
  6. once u reach to this point, move from prototyping to actual game play design. where things start to be very interesting.
  7. in this stage, u trying to maximize everything to looks cool and decent.

At least this is my pipeline as I’m a developer and 3D generalist for almost 5 years

Edit:
Dont try to make things complicated while u are working alone or even with very small team.

Hope this may help