i really agree with the guy whos posting all that experienced knowledge, but as far as taking lessons i have a different approach. when i started learning to play guitar ( by the way i have been playing for only 2 years but have recieved numerous awards of excellence in music theory, was just accepted to berklee college of music, and my band covers YEM...nuff said) but when i started learning, i really wanted to teach myself becuase having gone to regular school, i knew those methods of teaching were quite futile. so i went to different stores and loaded myself up with books on music theory from all ends of the spectrum. i read and read constantly, alot of the things i kinda understood, but just figured i would eventually fill in the blanks, so while i was still struggling with scales and intervals, i was rapidly learning concepts of harmony and improvisation. after i knew alot about things i truly didnt know about, i finally took 10 weeks of lessons. i thought the way i learned was great because when i sat down with the teacher he wasnt just showing me things his own way, when we sat down, i fired questions at the teacher filling in blanks and gray areas like it was my job. so i really felt my time was well spent(and money) so in short, i learned alot and got confused by alot so i loaded up as much as i could, asked questions for ten weeks, and designed a learning plan for the next ten weeks. setting goals is key for me in learning music theory, but i wanted to do it by myself. but at the point im at now, you cant buy books or look online. once you get into the hardcore jazz theory you gotta go back to school, but dont underestimate what you can learn for free from books and the internet. so before you go get a teacher, try doing it yourself, then asking questions to someone who knows, but thats only how i learned
