Have a single, unique place for every thing to return to.
I visited a factory when I was young. Halfway through the tour, I saw a tool wall. But unlike the tool wall in my uncle's workshop, these tools were outlined in red tape.
The tape showed where the tool was supposed to be. You could tell at a glance if there was a tool out of place. Both the wall or a wayward tool could tell you the same thing.
It wasn't until after university that I realized the importance. If I store too many things in the same place, they get jumbled and I have to look for them each time. But with space for each item, they become easy to find and easy to put away.
Where do you store your ideas?