I have a log that I track every song I riff repeat begening to end. I write it down in a notebook I have with the title of the song, artist, rythm or lead and the date. I also put a note to the side of what techniques the song is teaching me.   I keep every song at 100% difficulty I just adjust the speed according to how challenging the song is.   Example: Metallica - Jump in the Fire (Rythm) (Palm mutes, Power chords, alternate picking)   12/19/14 - 75% Speed - 10 Notes Missed 12/20/14 - 75% Sp