Here's an example of walking bass in the key of C.
The chord progression is II V I VI7alt : D-7 / G7 / CM7 / A7alt.
The walking bass is usually made up of arpeggios, scale passages and passing notes. Approach tones can be used between chord tones.
Use the neck pickup and cut the high freqs with the tone knob if necessary.
I use the Mesa Boogie V-Twin preamp on the clean channel connected directly to the sound card and I'm adding a little bit of reverb in Pro Tools.