If you’re in a situation similar to mine, you have students that play instruments that you are not that familiar with. Just like everyone else I took methods classes and I am certified to teach instrumental music in secondary schools. However, I would not recommend all of my students that they take lessons from me. There are many who are much more qualified than me to teach woodwind lessons.
I am, however, very comfortable with voice, strings and percussion. For those of you who are not, here is a website that has lessons for voice, guitar, bass, piano, and drums. It’s kind or a rock lesson website, but has some valuable tip concerning the basics and technique.
Link: Music Trainer