Good question. I also want to improve my techniques and welcome good suggestions from our senior players/the pros. So far I have been using simple techniques that works quite well - basically just using the same notes as in the chords. In the beginning of a measure I will use the note that is the main note of the chord. So if C is the chord in a particular portion of the song then I hit C at the beginning of measure. But during the measure, for variety/interest, I use different notes in the same family of the chord. For the rhythm of the bass, just listen to various types of music and notice the way the bass player hits the notes.