Some backend patterns I almost always change when I join a new project

Whenever I look at a new backend project, I notice a few things that almost always cause friction later on:

\- unclear API boundaries

\- inconsistent database structure

\- configs and credentials that are hard to manage

I usually restructure these early to make things scalable and maintainable.

Curious how others handle this kind , would love to see different approaches or tricks people swear by.