As a beginner, my bass repotoire is fairly simple. If I'm playing with a rock or pop tune and I want to put "motion" in the bass line, instead of sitting on the tonic, I'll jump up to the 5th and the octave, then back down again. I'm sure that those of you that have more bass skills than myself can see why a newbie would do that -- your index is on the tonic, and you just drop finger three two frets ahead and you're done. If I just ride rhythmically on the tonic, the song often tends to be flat. I know my scales, and I know what I guitar player would play to add notes. I'm looking for guidelines; I want to know why good bass players make the choices that they do. If you want to connect one chord to the next by adding some incidental notes between the two, where do you go? I hear a lot of bass players jumping up an octave in their bass lines, which is what led me to start abusing the fifth. Is the third a better choice? Thanks in advance!