1. Any idea that comes in your head, jot down in a card or list. This is just to get in the habit.
You may sometimes write a full page about the idea, sometimes it’s a sentence.
2. Quick triage, is this for “fame” (it’s just a small, time bound, scoped, fun project with no explicit objective or plan to earn money), or “fortune” (you’d only want it to be a business, prepared for months and years of work), both are fine
3. For “fame” tasks, pick ones that scratch an itch where you want to learn something or solve a problem (simple website, VS Code plug-in, OSS repo on GitHub, a tool/script you wrote and use locally you want to offer to others as a website, etc) something that’s time bound and has a very simple and complete scope.
4. For “fortune” tasks, decide which ones you feel are interesting, you have knowledge about the problem personally, you see revenue generation possibility, you can do it on your own or with minimal resources to start, you know it’s going to take years, but you’ve got something encouraging/progress to show yourself within 1-2 months
That’s how I think about ideas lately.