The first thing to determine is how you see things. How does your brain work? Some people need everything on paper in a notebook where they can physically touch a page - while others like to store items on the computer. Do you need it to be accessible everywhere? Like in the cloud?
It took me about 2 years of trying everything I could think of before I settled on OneNote. And it’s fine if it takes you awhile to find what works for you. Here are some options.
In my DE Series notebook I have the names of each character on the left – in their notebooks (like having a folder), my timeline, my settings, my magical systems, etc. Then within each folder you can create as many pages as you want and they all show up as separate tabs in the center. Then on each page you can type anywhere on the page and you can in drag photos. The reason this system works well for me is that while I’m writing or editing and I add something (like a character’s tell or new hairstyle) I can immediately copy it and paste it into the correct sheet in the correct notebook in less than 10 seconds. I want to spend as much time as possible creating my content and as little time as possible tracking it all J
I encourage you to experiment and find what works for you knowing this is anything but a “one size fits all” journey :)