Tariq,
Just finished reading an article in the Jan 2013 edition of Acoustic Guitar mag. On page 64 there is an article entitled "Fingerstyle Bass Lines" "how and when to use walking bass lines, pedal tones, and bass riffs in your compositions and arrangements. Just what your looking for I believe.
If you can't obtain a copy I believe there is on-line access.
www.acousticguitar.com
Blues