I write down all my ideas in a Trello board, and make sure that they're either easily actionable (can be done in a couple of days at worst) or tag them to split

I write down all my ideas in a Trello board, and make sure that they're either easily actionable (can be done in a couple of days at worst) or tag them to split them up later. My columns are Todo, In progress, Done and Backlog. Anything that's not a priority right now goes to the backlog. Every once in a while my Todo column gets empty, so I make a release and take stuff from my backlog. Any time I have an idea, I instantly write it down and stop thinking about it. This lets me focus on my task at hand.