Tips for building a second brain

I feel like I need to make a change. There's too much going on inside my head :D I have a multi-tasking job requiring me to manage AND market multiple products at the same time, while I'm trying to keep track of goals relating to personal development, side projects, and my learning curve in clinical psychology which I'm currently studying as part of my journey of becoming a therapist. I need a way to organize my brain because there's too much going on. I've heard the term "second brain" and did some research. Looks like Notion is the tool I'm gonna use but if anyone has experience with this idea and can relate to what I'm feeling - I'd love to hear thoughts / tips / things to avoid / any type of advice.