More questions! This is not a flood, I just have a lot of questions stored up. For me, the most important bass/guitar concept I ever learned was how to shift properly. Before I figured out that you *SLID* your fingers into the note, I let go of the string entirely, and then mashed the finger back down where it was supposed to go (more or less). To sound any good I had to stay in one position. Ever since I found out how to shift smoothly, bass and guitar have MADE SENSE. So what is your most important concept?