I once attended a song writing workshop with Darrell Scott and he said something that I found really interesting. He grew up playing in a working, family band. From a very young age he was playing back up guitar on stage every weekend and later, more nights every week. He said that becoming a strong, backup player would later become his most valuable asset as a song writer.
Knowing how to hold the rhythm and support singers is just as important, if not more important, then being able to rip out hot leads. My advice is to spend time on becoming a competent backup player first.
Here are a few helpful places to go to pick up tips for learning good strumming and flat picking technique. I’ll keep adding to this list as I discover new resources and if you find anything you think would be helpful to share, be sure and pass it along to me.