This is my personal approach to playing
over changes and to a great extent composition (there really isn't
any difference). If you want to know how to say a lot with a little
(I hope that's everyone) then check this out. I've included an original
Bb blues as a demonstration.
The ideal is to be a "combination"
player (position and single string combined), but that doesn't mean
thorough practice "in position" isn't essential. This document
goes through all the triadic and seventh chord arpegios and diatonic
intervals from the lowest to highest available notes in the key of
C major, second position. The fingerings are designed to avoid unwanted
sustained notes. Make sure to apply this approach to each position,
every key, and every scale. It will take a while but you'll find it's
a very efficient way to practice.