Yes to writing everything down and yes to google keep. I am now trialling using ticktick and obsidian but google keep stays as its simplicity makes it the perfect tool for quickly capturing thoughts before they fall out of your head forever.
I also majorly thank myself for the few things I indexed when I started a bullet journal. Everything I need my driving test ref it is so satisfying to go to the contents page and find the page number where the ref number is written down.