Playing with some of the methodologies like GTD and others is a good way to get started. A lot of it just has to do with getting thoughts out of your head and into either a text file or physical media. Personally I use a mix, I use digital for things that are nicer to cut and paste, and a journal that I date every page with.

I found the biggest improvement is having separate journals for 'projects' and 'day-to-day' as the writing for both is entirely different. A project in this case is something that doesn't have a distinct end. Watch and take notes on a youtube video? That goes in a day journal. Watch a series of videos on youtube that is going to take you a couple days? That goes in a project journal.

Trying to merge everything into one is what killed me.