The most important aspect of walking bass lines is the "feel"! While you are trying hard to "cop" my licks, remember to emulate the actual feeling and guitaristic nuances/dynamic shading that are happening. The technique will come if you practice diligently, but the FEEL of what I am doing is far more important. Listen closely! It's a good idea to practice developing strong bass lines WITHOUT chords first, then add the chords later.

Blues in Bb PTab
Blues in G PTab
Fast Blues in G PTab