A vastly underestimated way of accompanying is a very simple and effective one: play what the bass player plays!
This is especially powerful at the beginning of a song and leaves enough space for a singer’s first chorus or a soloist’s opening riff.
Depending on the type of feel, you could use one of these examples. If you want to avoid a beating with the neck of the bass, listen to the bass player before you get in his way.
Here is a simple one. This ‘walking bass’ can be used in Chicago blues and swing blues.
There are a thousand different ways of playing a bass line like this.
The feel can be altered by playing each note staccato (damp the note quickly after it’s been played) or legato (glue the notes together by keeping the time between notes as short as possible).
B.B. King’s backup guitarist might use something like this on “Caledonia”.
In bars 5 and 6 you’ll see that the bass line starts with the root of the IV chord C and that it uses the notes of a C major pentatonic scale! Whenever you use major pentatonics you’ve got to follow the chords. G major pentatonics over G7, D major pentatonic over D7, etc.
Notice how bars 4 and 5 glide into each other chromatically, a feature used a lot by bass players. This way of playing chromatically through the chord is also being used in bars 11 and 12. Instead of using just the major pentatonic scale, you walk through the changes and hit the root of the V chord D at the beginning of bar 12.