Best resources to improve session_state and app flow understanding

Hi,
This is a question for the community… What are the resources that helped you master session_state and general application flow? These could be anything: posts in this forum, articles, videos, etc. Asking because I feel like I’ve spent time trying to improve in this area, but I continue to struggle in this area once my apps get to a certain level of complexity.

Appreciate any advice. Thanks!