Projects - for all sorts of stuff that can be anything from little one page apps, t-shirts, art projects, do X but for Y (like do this thing somebody did for US states but for European Countries), slogans to print on beer mugs - whatever.
Serious Projects - anything that will take several months of sustained development to be able to make an MVP and will require funding of some sort.
They're just on google drive, I figure if I get an idea on the bus and it can't last til I get somewhere to enter it in my projects document, it isn't a worthwhile idea.
(1) I have an asana project called Ideas. Each task is an idea. I've set up a workflow where I can just send an email to the Asana project inbox and a task gets created. I've kept up this practice for more than a year and I have almost 300 ideas I've logged.
(2) Whenever I think 'alright, I want to work on a new side project', I go through the list of ideas and categorize them. A ton get categorized as trash, and a very small number get categorized as worth moving into customer discovery and validation.