I am using DEVONthink for some months now. I use this tool on my computer to safe fragments of pure text in a database. As a result I am able to navigate, search and browse through my saved notes.
There are alternatives for other plattforms like Windows. My flatmate is using Microsoft OneNote to do similar things. You even do not need a special tool for that, since modern Operating Systems index every file so that one can do a fullterm-search on the computer within some seconds. But for now it is just important that the reader gets the idea of the principle.
DEVONthink is document management tool with the already mentioned associative search engine. I think it was a book by Steve Johnson who mentioned in a book that he was using DEVONthink. (In the past) authors used slip box systems while they did their reasearch for a book. Every information they could find was written down on a index card and categorized. After they did their research, they outlined everything, ordered their notes and finally, they started to write out their notes.
I use this technique to outline thoughts and categorize them with tags. I started to write down cites (‘I’m a fruitarian and I will only eat leaves picked by virgins in the moonlight’ – Steve Jobs). I save my own howtos, eg. how i configured thinks on computers and in tools, how I have to crop images for my web page and so on.
Hopefully this inspires you to write down stuff, thoughts and notes that you have saved in your primary brain. As soon as you start to write down these things, you can use your real brain for other important things : ) Another positive fact is that you can start to see your thoughts and notes from a different point of view. Then you can combine your new notes with older ones, that you already had forgotten in the past.