I started playing bass with a blues band when I was 14. The other band members were all in their late 20s and early 30s. The guitar player was also a local bass player for other blues bands. (We lived on the same street and practiced at his house, which made things easy for me.)
He first taught me a riding/pedal bassline, which is a single note bassline that really helps learn the feel of the blues and how to swing… Further On Down the Road (Eric Clapton) and Tush (ZZ Top) are both good, popular examples.
After that, I learned three “basslines” for walking blues:
- 1, 3, 5, b7
- 8 (octave), b7, 6, 5
- 1, 8, b7, 5
I later learned that these are (mostly) based on arpeggios for Dominant chords.
The next challenge was to begin replacing the bassline with chromatic notes when changing chords. (i.e. When changing to the 4 chord or walking back down to the 1.)
A 12 bar blues usually follows this formula:
- Four times on the 1.
- Two times on the 4.
- Two times on the 1.
- One time on the 5.
- One time on the 4.
- Two times on the 1.
Tommy Shannon uses all of these very often. I agree that he is a great learning example for walking bass.
Walking bass with Jazz becomes a little more involved, and can take knowing some theory, depending on the style.
I would say that walking country music can also be a little more difficult when learning because the chords tend to be simpler than blues and jazz chords, which means there are less notes in the arpeggios. Dominant chords usually have 4 notes which makes it easier because each “count” gets a new note.
This is obviously a simplification of what actually going on in most walking basslines, but it was a great jumping off point for me as a young player. I hope it can help you too.
Let me know if any of the explanations are too vague, and I will try to make a finer point.