being a self-taught pianist myself, i have come to realise the various weaknesses and deficiences a self-taught pianist may have.
in particular 2 difficulties stand-out.
one is self-motivation - a teacher will set a task to do , lets say - learn a short piece or a single movement of a sonata in a week.
being a self-taugh pianist, it is hard to discipline and motivate ourselves to do things like this..
seconds, FINGERING is a huge concern, there is much trial error and time consuming effort involved in understanding which fingerings work best.
there is the famous story of liszt, hwho had been semi-self taught up until the age of 12 or so, when he auditioned for czerny - czerny was disgusted by liszt's completely impractical and undisciplined fingerings, but was amazing by his raw talent..
the point of discussion i wish to bring up, because it really is INEVITABLE that many pianists will remain slef-taught, to to stubbornness, or financial situations etc...so no 'get a teacher' preaching....
what are the other potential perils of being a self-taugh pianist, and secondly, what are the best ways, if possible, to overcome them?
I went the teacherless route for a while, and did pretty well for myself I like to think. Eventually I decided to try lessons with a teacher to really find out what all this "get a teacher" business was about, the value of a teacher wasn't quite what I'd expected.
Motivation has always been an entirely personal thing, exclusive of whether or not I had a teacher. Whatever happens in the lesson doesn't really have much effect by the time I'm back in the nest of my home. Though, a teacher will have valuable insight to help you figure out what kinds of goals you would like. Like anything else in lessons, it's a teamwork between student and teacher - if you haven't the slightest clue what you'd like it's very difficult for a teacher to help point you in the right direction. I believe that anyone who was once a child has to at some point learn to motivate themselves to do things for themselves.
What I found to be the most valuable aspect of a teacher is the feedback. No matter how thouroughly I think I'm evaluating myself it seems there's some aspect or another of my playing that I'm completely missing out on. A teacher has more playing and listening experience and will spot right away what you're not even aware of. Mostly interpretive considerations; style, ornamentation, dynamic control... Polishing up the playing once the notes are learned. Or if the student is having troubles getting the notes under the fingers, help with that. Sometimes I'll have the notes all learned, but in the wrong register, which a teacher will catch and correct.
There are countless aspects you could miss that a teacher would catch. For some it may be tension that proves fatal over time, that could have been prevented.
Also, a teacher can provide you with performance opprotunities. Afterall, that's what we work so hard for in practice - to share the music with others.
As for self-teaching, it's also crucial to be your own teacher since in between the lessons it's all up to you. I do as much reading as I can on my own, this forum is an incredible resource in itself as well as in book/video recommendations. Everyone who posts advise becomes a teacher, and every books author has something to teach. I order the books/videos when I can afford it and when I can't I scour the public libraries.
Also, check out your TV guide for music programs. I was surprised to find there was 12+ hours of music performances on each week. Program the VCR and before long you'll have a library of music to view at your leisure. There's much to learn from watching other pianists playing, also inspiration!
The more information and ideas you have floating around your head, the more you'll have to try at the keys.