I will one thing: apt pinning[1]. It allows you to tweak the way apt choses the version to install, and allows you through a configuration text file to give higher (or lower) priority to specific releases, repository components, repositories, package names, etc.

I started using it before 2005, before backports was a thing, and it was a lifesaver for my desktops, as I usually wanted to use newer versions from testing or unstable.

[1] https://www.debian.org/doc/manuals/debian-reference/ch02.en....