Comme le vent is right: a teacher will be a great help.
However, with or without a teacher, you should be aiming not only at playing a specific piece, but at having a well rounded musical education.
You will need to train yourself (or be trained) at least in the following major areas:
1. Sight-reading
The best reference I came across is Howard Richman’s “Super sight reading secrets” (Sound feelings). Just follow the suggested course in the book.
2. Ear training
An excellent step-by step course is given in : Colin Aston – How to play by ear correctly (39 Church Way, Longdon, Rugeley, Staffs, UK)
3. Theory and harmony
You will need that to figure out how music works. Three very approachable references are:
Eric Taylor - The AB guide to music theory (ABRSM – 2 vols.)
Robert Jacobs – Understanding harmony (Oxford University Press)
Ward Cannel & Fred Marx – How to play the piano despite years of lessons (Chappell)
4. Technique
Try Seymour Fink – Mastering piano technique (Amadeus). Make sure you get the accompanying video.
And Gyorgy Sandor - On playing the piano (Schirmer).
If you find these a bit advanced (buy them anyway, you will need them eventually), a good beginner’s primer is
Seymour Bernstein – 20 lessons in keyboard choreography (Hal Leonard)
5. Repertory
Acquiring technique and learning theory is not that time consuming actually. A determined individual with correct guidance should be able to master everything in one – two years. What really takes time – especially at the beginning – is the acquisition of repertory. So, from the very start you must familiarise yourself with as much of the piano repertory as possible. In the beginning this means listening to a lot of CDs, surfing the net and reading Piano forum! Eventually you want to start getting the scores for your favourite pieces and sight read through them, as well as have a systematic plan to learn them. Consider this: if you learn five pieces a year (a very under ambitious goal), at the end of 25 five years (you will be 46) you will have 125 pieces in your repertory! Alfred Brendel in an interview said his repertory was around 150 pieces. And he is in his seventies!
Also, 90% of the piano repertory is actually not that difficult to play. So make sure that your pieces follow a reasonable progression in terms of difficulty: amongst your favourites, learn the easy ones first.
Add to that composition and improvisation later on.
Make a long term plan (what you want to achieve in say, 5 years time), then map what you will need to accomplish in a medium term (months) and short term basis (weeks/days) that will add up to you long term goals. Then be very consistent about it.
I hope this helps.
Best wishes,
Bernhard.
Topic: Timetable?