Monotonic-bass fingerpicking, in which your thumb keeps playing the same bass note instead of alternating between two or three notes, is common in acoustic blues but works great in folk and rock, too.
You can rock back and forth between a monotonic bass line and plucked treble notes for a piano-ballad style of accompaniment (Example 6a). This backup works for many types of songs, and Example 6bshows it at work in a progression similar to Clapton’s “Tears in Heaven.”