Well, I'm pretty new to this but this is what I've been doing. I look at a lot of youtube videos and often find 2 or 3 that are helpful. As I get more into it, I type up the lyrics, print it out, write chords on top. If they are chords I'm not too familiar with or variations on something I am familiar with, I have a rubber stamp that is a chord diagram that I'll put in the margin and pencil in the fingering. I may pencil in numbers here and there and then, on another page, a footnote (e.g., "try to play these chords with a stacatto kind of a feel"). I likely also will print out a tab sheet (I make these in excel) for sections where that is helpful. However, because I am not able to accurately figure out and notate the timing (like if something is a dotted half note or syncopated or whatever), I am interested in starting to create a library of sound or video files with me playing the song, that I can refer back to to refresh my memory of how it is suppose to go. Almost all of the songs I do are more accurately described as renditions rather than straight copies of the original so I can't just refer back to the source.