That's a topic I'm more and more concerned about everyday. I'v been working it for the past year as I had to reinstall different machines of mine multiple times, be it a server, phone, or desktop.
The first step toward it (and the most consequent one) was to learn how to NOT customize softwares. If you dont have any dotfike, then you dont need to manage them. It doesn't sound like rocket science, but its actually helpful. When you login to a virgin system, all you need to do is installing the software you need, and you're good to go! By using default configs, you also spend less time configuring things and more time using them.

Another point I'm still working on is the persistence of data accross installs. This can be done using things like NFS. But I dont have something 100% working yet.
This also include deployment of new SSH keys and password managers, so this point is a bit touchy.

And last, but not least: Deciding what I want after the reinstall. I'm still not 100% satisfied with all the distros out there, so each install brings the question on the table (i currently run 6 different OS across 8 machines)