Having spent my life giving guitar lessons, you might suspect me of having a biased view of this subject! Let me assure you at the outset that I do not. Even though there may be a small part of me somewhere that does think that everyone should take guitar lessons, (whether they plan to actually play the guitar or not!), I always keep that part under control, and never let it sway my judgment!
So don't worry, you're in safe hands here. In fact, there have been times in my teaching career that I have actually told a student not to take lessons anymore, or to go to another teacher. So I don't make any blanket statements about taking guitar lessons. The way that lessons, or the process of educating yourself as a musician, fit into your life will be a decision you make based on your unique circumstances, and your unique goals.
One general statement I will make is that for beginners, lessons are ALWAYS a good idea. This doesn't mean that you should make no efforts to perhaps teach yourself, using books, videos and the Internet. But along with all of that, especially in the beginning, and especially if you have no previous experience with music, you should seek out a teacher.
If you are teaching yourself, and coming along well, then lessons will increase your progress, usually greatly increase your progress. I started by teaching myself for about three months. I was learning and could play lots of songs, and was teaching myself to read notes from a method book. But when I started lessons, I really started to make progress, simply because of the guidance of someone who knew the route to take a lot better then I did. Also, and most importantly, a great number of misunderstandings and wrong steps were corrected by someone who had two things I didn't have: knowledge and experience.
Re-Inventing The Wheel?
Let's get a few things straight right at the beginning. Let's really look at this question, "should I take guitar lessons?" I have to tell you, whenever I hear a beginning player ask that question it makes me laugh. It's like a five-year-old saying they want to be a doctor or lawyer when they grow up, and asking if it would be a good idea if they went to elementary school! The mere asking of the question shows how much the person asking doesn't have a clue about what they are getting into, and how best to get into it.
When I hear this question, I think "why on earth would it ever be a bad idea to learn a very complicated subject from someone who knows a whole lot more that you do, and has years of experience with the subject?" Why on earth would it ever be a bad idea, before beginning a journey to an unknown place, to ask for help from a guide, who has traveled the route many times? The very fact that someone is asking the question shows they don't understand how the whole process of the development of talent works.
They don't understand, for instance, that playing the guitar is a very sophisticated mental/physical process. Like many activities, such as various sports (tennis, golf, basketball) it has evolved over many years, and continues to evolve, becoming increasingly complex, and new standards of excellence being set all the time. Would anyone seriously ask the question, "would it be a good idea for me to go to baseball camp?", or "would it be a good idea to take tennis lessons with a tennis pro?", or "I'd like to improve my golf game, do you think I should take lessons with Tiger Woods, or his teacher?". We all know the answer would be "Duh!!?!!"
Yet, when it comes to learning the guitar, people somehow think that perhaps it might be a good idea if they shut themselves up in a room and spent their time re-inventing the wheel!
Why do so many people adopt this attitude as they begin guitar (and many people do, bear with me if you are not one of them)? Here are the reasons:
Ignorance: Plain ignorance about the entire subject of education, that is, of learning anything. They don't understand that ALL resources, such as books, videos, watching players, talking to players, as well as sitting with players who make a regular habit of transferring their knowledge and abilities to others (teachers) should be used if at all possible, ESPECIALLY in the beginning.
Intimidation: They imagine they would be just plain embarrassed fumbling around with something new and looking and feeling like an idiot in front of a stranger.
Illusion: they look around and see people who just "pick it up" on their own (or at least say they do!). They don't understand that some people have "natural talent", which is the tendency to do the right thing, but that even those people would go much further with lessons, and may very possibly never get as far as someone with less talent who does take lessons. Sometimes people see other people who just "pick it up" and say, "I should be able to do that", and doggedly keep trying to learn on their own, even though nothing is happening, and they aren't learning! Just like men who won't stop and ask for directions, it begins to become an ego thing, and leads to the in-ability to recognize that we need help, and to put ourselves in the vulnerable position of asking for it.
Ego: They want to feel like they HAVE re-invented the wheel. This one especially gets people who do have talent, and can get relatively far on their own. They really like the idea of being able to brag to people that they are "self-taught". The psychology of this one is very similar to the syndrome I expounded in my essay "Why Should I Learn to Read Music".
Money: Well, we can't argue with this one! Sometimes people just don't have the bucks for lessons. Personally, at one point in my life I worked 20 hours a week in a factory for minimum wage and spent it all on my lesson with a top teacher in New York City. I put off having a car and used to hitchhike to get around so I wouldn't have to support a vehicle. We all decide the price we will pay for what we want.
So, if you are one of those people with a bad attitude about taking lessons, decide which of the above reasons applies to you, and whether you want to deal with it or not.
You Already Have A Guitar Teacher!
It is very important to realize that even if you are not taking lessons you already have a teacher. YOU! Understand that especially if you are not going to someone else for guidance that leaves YOU in charge of your own growth, and responsible for your progress. It leaves YOU as the ONLY teacher on the scene. And you better make sure this teacher is a good one! You better make sure this teacher is honestly working their best to make sure the student is learning how to play, and play well, and building the foundation for continuous growth.
The job of the teacher is two-fold: to present new material to the student and to make sure the student is actually learning it. If you are your own teacher, these jobs fall to you. Just like buying yourself a book to present yourself with new material, buying yourself some lessons is fulfilling the same teaching function.
And besides, if you are your own teacher, and doing a good job, sooner or later you will arrive at the conclusion that it would be a good idea to get some assistance from someone who has already given some, or many, years to playing the guitar and being a musician.
True, you never know if you are going to find a great, or even good teacher, at least right away. However, a teacher would have to be pretty lousy to not be of SOME benefit, at least for a while. You can always leave and look for another, and knowing WHEN to leave a teacher is an art in itself!
No One Is Self Taught - Everyone Is Self Taught!
The fact is, in one sense none of us are "self-taught", and in another sense, we are all "self-taught".
None of us are self-taught, really. We are all influenced by what we see and hear around us, whether we are aware of it or not. A baby learns to walk by watching others walk. It doesn't take "walking lessons", but without watching others it would never learn to walk, (or talk, for that matter). So, the baby doesn't take lessons, but would they be justified in going around when they're about 10, bragging to their friends, "Yeah, walkin', taught myself!"
I don't think so.
Segovia went through his very long life telling people he was "self-taught". It was great PR, and the press loves that kind of stuff. He liked to give the impression that he started the classical guitar from scratch. Of course, he did add immeasurably to the domain and reach of the classical guitar, but only by thoroughly learning what came before him. There is a great picture of him sitting at the knee of Miguel Llobet, (the main student of Francisco Tarrega, who was the greatest guitarist of the 19th century, right before Segovia began his career.) Segovia is watching intently as Llobet plays, and you better believe he is absorbing every detail of what and how it is being done. He is "taking a lesson".
If you play electric guitar, or folk guitar, or any style for that matter, one of the best things you can do is watch (and listen to, of course) other players. If your inner teacher is functioning, you will pick up something every time. You may not know it, it might just appear, show itself in some way, the next time you play.
The great players are doing this all the time. They were doing it when they first picked up a guitar. They MADE everything be their teacher, whatever happened to come their way, other players, recordings, and teachers. This kind of aggressive attitude is essential, and this kind of aggressive attitude would never even ask the question "should I take lessons". It knows the answer would be, "Yes, if you can".
The real teacher is the "inner teacher" we all have inside of us. If that teacher is not on the job, no learning gets done, no matter who is standing in front of us playing the role of teacher. That is the sense in which, ultimately, we are all "self-taught".
It is this "inner teacher" that recognizes and makes use of all the "outer teachers": people, books, etc.. So, in the sense that we will, and must, be absorbing knowledge and influences from what is around us, none of us is "self-taught".
When To Stop Lessons
I have said lessons are always a good idea in the beginning. As you move along, there may be times when it is best to stop lessons, at least for a while. Sometimes, we simply need to be alone with our playing and our development for a while in order to reach new ground, the place that is right for us to grow into.
Especially for players of improvised styles, where the activity of playing with others is so essential to the growth process, this can become an important consideration. And often the student doesn't recognize this. There have been many times when I had a student who was happily spending all his time learning scales and doing exercises, but couldn't jam a simple blues solo with another player! If someone like this tells me they have aspirations of being in a band, I will tell them "stop lessons and join a band! It is more important for your development to play with other people with what you already know, than it is to stay in lessons and learn more scales or exercises!"
And this leads to the understanding that the need for lessons is not only different at different stages of our growth, but it is also different depending on the style we wish to play. As time goes on, lessons are less important for the blues./rock player. Actual playing experience is more important. The same is true for the folk player. Only when Vertical Growth is desired are lessons necessary. A great blues player becomes great because they are steeped in the language of blues, and speak it all the time as they converse with other players. You cannot become a great blues or rock player by staying in your room or taking lessons for the rest of you life.
If you are going to pursue the classical guitar, you'd better get some lessons right away, and work hard to make sure it is with the best teacher possible. Also, you should expect to be in lessons for at least ten years, if not the rest of your life, depending on how professional and developed you desire to be.
Summing up, understand that even if you are not taking "formal" lessons, you still have a teacher, and that teacher is you, and you have the same responsibility that your teacher would have if you WERE going to formal lessons: you must make sure the student is learning, and if not, you must do something about it.
If you are taking "formal lessons" understand that even though there is someone sitting there who has the title "teacher", YOU are really the teacher, you are really the one who decides whether anything is going to be learned, and who actually does the learning. You are going to decide how effective the lessons really are by how well you apply yourself.
If you are in lessons and not learning, than your "inner teacher" must tell you it is time to leave, and time to begin the active search for another teacher. Many people don't do this, and that is why they can be in lessons for a long time, and not be learning.
Teaching and learning are in reality two sides of the same coin. You cannot become a great teacher unless you have already been a great student. Realize that you must play both roles in the process of your own growth as a guitarist.