You should be able to use your voice well.
You should be able to write well.
You should be able to play your instrument(s) well.
Most performers I've seen live are good at one or two and at least passable with the third skill. Two out of three is not bad because it takes a good deal of work to get to that point. However, to be considered a triple threat we singer-songwriters should really develop and master all three skills to be our best. I took guitar lessons for one year– twelve years ago– and that's what I sound like when I play the guitar. So now I'm working to improve this skill.
Recently I read an interview (by Derek Sivers, CD Baby founder) with touring musician extraordinaire, Amber Rubarth. After reading about the hours of practice a day she puts into her music I was inspired to go on a search for a tutorial-style book to work on improving my guitar sound. After a couple hours at bookstores and then my local library I finally picked up this gem: The New Complete Guitarist by Richard Chapman.
I'm only about fifty pages into it but I love that it is very visual and packed with information about my instrument (an acoustic-electric cutaway). It also includes info about other types of guitars with historical tidbits. It's like the music book equivalent of the TV show Good Eats. Hey, I might even learn why the guitar neck's 12th fret has double dots. Does anyone really know about that?
Another thing you may not know is that this is February Album Writing Month. If you're interested in the challenge of writing fourteen songs in twenty-eight days let me know so I can add you to my watch list. If you want to follow my writing progress, here is my page: fawm.org/fawmers/madeline/
Happy music making!