I've come across a lot of different series and 'methodologies' (Aaron Shearer, Mel Bay etc) books - and it's very confusing for the beginner when there's no teacher to guide him or her.
If you do not have access to a teacher, I recommend choosing a program that will provide you with corrective feedback so that you may fix your mistakes in order to progress. In my experience, lacking this feedback you may unknowingly develop poor habits, both musically and technically.
Fixing your mistakes requires seeing and hearing correct playing. So, a multimedia instructional program may be your best choice. I recommend looking at Frederick Noad's books with CDs/DVDs. (He published his first multimedia instructional program in 1963, which came in the form of a book and weekly television program. See attached photo of my copy.) Today, you would probably do well to try Noad's updated text:
Noad's books are well-respected by many classical guitar teachers. So, if you decide to ultimately take lessons, you may find the transition to be a smooth one.
For classic guitar I recommend:
- The Christopher Parkening Guitar Method, Vol. 1
- The Christopher Parkening Guitar Method, Vol. 2
These were published in the early 1970s by the great virtuoso Christopher Parkening with Jack Marshall and David Brandon. They are highly regarded by guitar teachers. The newest edition comes with a CD so you can hear what the lessons sound like when they are played correctly.
From the publisher's description: "The method covers: rudiments of classical technique, note reading and music theory, selection and care of guitars, strategies for effective practicing, and much more. The CD includes 99 demonstration tracks."
I havent looked at beginner books recently. But I can offer a rule of thumb:
- A Real Classical Guitar Book will contain no tablature. It is very important to "take the plunge" and master staff notation.
The book I used and was very happy with was The Romero Method, by Celedonio Romero, but it looks like it's out of print. :(
There is a book by Son of Romero that's probably worth checking out. (These guys were breaking into The Tonight Show, while Segovia was breaking into Carnegie Hall.)
As one who is teaching himself to play classical guitar, I have found the following method books to be excellent. They are in no order:
Frederick Noad. Solo Guitar Playing: A complete course of instruction in the techniques of guitar performance* (4th Ed).
Aaron Shearer. Classic Guitar Technique (3rd Ed). Book and CD. (ISBN-10: 07390-57103).
Julio Sagreras. Mel Bay Julio S. Sagreras Guitar Lessons: Books 1-3 (English and Spanish Edition) [Spiral-bound]. (ISBN-10: 0786627239).
Jeffrey Goodman. A Beginner’s Guide to the Classical Guitar. (ISBN-10: 1439267499).
Robert Benedict. Sight Reading for the Classical Guitar, Level I-III.(ISBN-10: 0769209742).
Robert Benedict. Sight Reading for the Classical Guitar, Level IV-V. (ISBN-10: 0769212859).
The Aaron Shearer series of books (link to Volume 1) are well-regarded standards. They were first published in the 1950s or 1960s and are still in print.