Watch the Walk the Bass online guitar lesson by TrueFire from Play Blues Guitar 7: Fingerstyle Approaches
Walk the Bass - Lick #5 is a video guitar lesson presented by Joe Dalton and is sourced from 50 Acoustic Blues Licks You MUST Know.
Here's a good example of what you can do with variations. The melody from example 1 is now the bass line. This is a good start for creating a walking bass line. Notice the subtle use of the open strings. Although they are used sparsely, these single open notes add a lot to the feel. I often use this pattern to move from the 1 chord to the 4 chord or from 5 to 1.