- a physical notebook (I always carry it)
- nth-priority-ideas.md file (I write down ideas)
- I have an on-and-off relationship with Evernote (as it is easier to sync it with phone and other stuff; though, cannot draw as easily as in my notebook, and not as distraction-free as a single Markdown list)
Most importantly, if I have no time for an idea (the best ideas stuck me when I am busy) I write it down and forget.