IMO walking bass is best practiced while playing a chord progression to an actual song. Walking bass is not all that hard. You move from one cord to the next using passing notes. This can be one note, two notes or a three note walk. Say you are using the old R-5-8-5 a one note walk would be R-5-8-X with the X being one semi note from the next chord.
I make it dirt simple by targeting the next root note then miss it by three frets. I then walk to the root note one chromatic note per beat. Trick is to time when you leave on your walk so you are on the next chord for the change, i.e. hit the change dead on. That is the dirt simple way. Is there other ways? Of course, books have been written on the subject...
What does the walk accomplish? In Country the guys hear the three note walk and know a change is coming. The walk leads to the next chord.
Ed Friedland's book will be time well spent.
