Be sure to check out Dale Turner's series of lessons on Campfire Chords with Character. He explains how to create more interesting chords by adding extra notes. He gives several strumming and fingerstyle examples that sound very much like "singer-songwriter" playing. I think you'll like it. I'm not a great player, but I'm sure I can use some of what he teaches to make my playing more satisfying (to me and anyone listening!). Good luck.