I am mainly a singer/songwriter. I can play many techniques like slap/pop/tap, arpeggios etc... I try to write chord progressions with walkin bass notes at the bottom while singing. Adding little riffs and changin chords then tapping and coming back to the main chords etc... (Nathan Hughes - Seth Horan style) My harmony - fretboard knowledge is weak. I already study them right now bUT I need tricks and tips to learn how to write 2 or 3 note chords in a row on bass? and little riffs- taps in between..... Or can u suggest me any good books or dvds? What kind of knowledge should be my main concern in order to play the bass like a singer who plays rhythm guitar lets say?