My teacher showed me this exercise at my last lesson and it's really helped me improve my walking. It's simple just walk a few chorus's of a tune with out going above the 5th fret. Then walk a few playing only between the 5th and 12th frets. Then walk a few only playing above the 12th fret. Oh and open strings are ok no matter where on the neck your playing between. sorry if my wording is unclear I'm really tired.