I teach classical guitar, electric guitar and electric bass guitar to all ages and levels. For children ages 4-8, I recommend starting on the classical guitar using the Suzuki Method. To learn more about the Suzuki Method on the Classical Guitar go the Suzuki Guitar section.
To be honest, when it comes to beginners of any age, I recommend starting on the classical guitar for a variety of reasons. I find that studying classical guitar, regardless of personal music preferences gives the beginning guitar student a solid technical and musical foundation as well as a clear path of development which I think every student needs initially. Transitioning to other styles actually becomes easier with this foundation in place. To learn more about guitar types, their uses and sizing please reference my Guitar Types page.
Check out a couple videos of my past students below. The first is Mia playing a beautiful rendition of Valse Espagnol from Suzuki Book 5 and the last is Benjamin who I taught for 14 years who started on Classical as a Suzuki Student and has now become quite an electric guitar player. He still plays classical.