I think the easiest way to learn this is to learn all the different variations of tri-tones for each chord, starting with 3-b7. You're probably already playing this. If so, then try partial or full chords. If you play the organ this is easier to learn, in my opinion, because then you can play the bass with your feet and practice playing songs with just your left hand and foot. When doing this, however, you'll probably start out playing the same thing that your right hand would play, but the object, ultimately, is to play harmonizing chords. To get a basic of this, you should start out listening to other groups that have advanced musicians.