There is a short article in the latest issue of "Electronic Musician" by Jim Alfredson on starting out learning walking bass. It's pretty basic but it sort of gets you used to left hand/right hand, left foot/right foot independence. I've been doing it for over 50 years now because of playing the B-3 organ. It's my claim to fame but I learned it gradually over the years. I was much younger when I started doing it with no life distractions like having to cook and clean for myself because my Mom did all that for me at that young age. I could stay focused in a sense.
I started out with imitating what the bass guitar was doing and then later on simply started out by outlining the chords of the tunes. I have since learned how to play the bass guitar and that helps learning to play convincing bass lines with my feet or left hand.