Installing Windows as dual boot on Linux computer

I am currently having my Dell XPS13 with Ubuntu 18.04.2LTS installed, and I am very happy with it (mostly doing dev stuff). Right now I am using a Windows VM whenever I need to use Windows application.

However the amount of applications without Linux support I have to use is growing so I decided to set up a dual boot system.
I installed a dual boot setup based on a Windows machine before and I read that this is the recommended way is to:

  1. Install Windows
  2. Add Ubuntu

So I was wondering what the best way is to realize this setup while keeping everything from my Ubuntu system (files, applications, …).

My thought is that I’d have to completely clone the system and create an .iso and use this one to install Ubuntu instead of the default one.

I just wanna know if any of you have done this before and what your process looked like (before I completely mess up my system).

Or at least I will create a backup so I can restore my Linux enviroment at any time.