1. I use Omni Notes (simple note-taking app) and Bear  to write down thoughts and longer texts. And a simple voice recording app  for bigger ideas that need more words.
2. After this, I evaluate them and add them to my personal wiki. I’m using BookStack  which is the best open-source wiki I’ve found. Every aspect of my life gets its own book with chapters and pages. It’s a pretty straight-forward structure.
I'm using this process for a year and it served me well (understanding life goals, writing down business ideas, structuring knowledge). Next step is bookmark management, I'll probably try out Shiori  (was once featured in a Show HN).