I jumped into walking bass without a whole lot of preparation. I've been at it about a year and half now. Nothing really came together in a way where I could actually sense that I'd be able to build my own lines on the fly till I used Todd Johnson's Vol 1 and 2. But my greatest praise goes to the full tunes section at the back of Vol 2. I've been on 'Autumn Leaves' for a few months now. And I don't really mind. There's a wealth of information and musical information in those 4 pages. Some days I'll play what's written an octave up or down or reverse the order so if a bar starts up, I'll go down and and vice versa. There are a lot of books and exercises available, but nowhere have I found such a concentrated well thought out and musical lesson. There are times when I can hear the sequence of what's being taught and it really begs for me to start improvising. A lot of books, esp. once they get to where not every bar has to start on 1, just sound like someone went for a random order and I can't hear how the sequence connects to much of anything. Brilliantly not the case with the pages I've been working on.