whats a good age to start learning guitar?

Any age is a good age to start if you want to learn to play. It's better to have lessons if you can find a competent guitar teacher or even a guitar-playing friend or relative willing to give you a few tips. You can avoid a lot of trial-and-error that way. It really depends also on how well you want to play. If all you want to do is to learn a few chords so you can strum along while you sing some simple songs, you probably can learn with some simple instruction books or videos. If you want to play some very advanced solo pieces, it may be a lot harder to figure out everything by yourself.

After all, there are Master Classes for guitar in which advanced guitar students or even professional guitarists who can play quite well, will go to learn from some even more skilled guitarists.

http://www.classicalguitar.org/classical-guitar-ma...

(No, I am not suggesting you start here)

Remember, even "untrained" musicians usually will have learned to play from observing others play or have had other musicians work with them, even if this isn't in a "formal" setting.

http://en.wikipedia.org/wiki/Jimi_Hendrix

http://www.madguitarlicks.com/eddie-van-halen.html

Start whenever you want, there is no law that says you must start by a certain age. Most people start in their teenage years although some people don't start until they're in their 40's. As for a teacher, yes get a teacher, but don't just get any teacher, get someone who understands the way you want to play and what you want to accomplish. You have to have goals, you will mostly learn theory from guitar teachers but a teacher with similar interests or even just someone who really knows what they're doing will be able to tell you exactly what you have to work on. I'm mostly self taught, besides using youtube and instructional dvds, and though I've come really far in just four years I'm still years and years behind the greats. The best thing for any guitar player is a thorough understanding of theory used in their playing and a lot of experience with fundamental guitar exercises. Guitar is a life long journey, you will find favorite chords, scales and equipment along the way. The important thing is that you play for you, don't play to make anyone else happy, just do what you need to do to be satisfied with your own talents and abilities, and as a musician I can tell you that once you start and as long as you stick with it, you'll never stop learning and you'll never stop growing.

Lessons and 10 or 11

Any age is good, preferably when you're younger. Lessons are better, however, self teaching is also possible- it depends how dedicated you are. If you lose interest or get bored easily I'd suggest lessons however.