Many students ask me a question that goes something like this:

"What all do I have to know to be a really good piano player?"

The trouble with a question like that is that it ignores individual differences such as talent, motivation, freedom to practice, and a hundred other variables.

How much did Mozart have to know? How much did Erroll Garner know? Mozart could play far better than I can when he was 3. And Garner was barred from joining the musicians union because he couldn't read music.

Does that mean I don't have to practice, since Mozart could do it without practice? Does that mean I shouldn't learn how to read music since Garner couldn't, and it sure didn't stop him.

Obviously, no.

I wish I had the talent of a Garner or a Mozart, but I don't. Nowhere close. But God gave me some talent, and it's that talent that I need to develop to it's maximum.

Same with you, unless you're in a class with those guys, in which case you certainly don't need me.

Back when I operated Piano University & Keyboard Workshop, we had a list of skills that we attempted to inculcate into our students, at least to some degree. Here is that list:

Technique -- the ability of your hands to do what your brain tells them to do.

Fingering -- which finger goes where, and why, and when.

Chords -- How chords are formed and all the variations from major chords to minor chords, diminished chords, augmented chords, and all the extensions such as 7th chords, 6th chords, minor 7th chords, 9th, 11th, and 13 chords, plus suspensions and alterations including flat 5ths, flat 9ths, etc.

Scales -- How a major scale is formed from whole steps and half steps. How the 3 forms of minor scales -- natural, melodic & harmonic -- are formed. How the modal scales such as Dorian, Lydian, Mixolydian, Aolian, etc. are formed. How chromatic and whole tone scales are formed.

Ear Training -- Developing the ability to hear intervals from 2nds to 9ths; developing the ability to hear chord types and recognize them; developing relative pitch.

Music Theory -- Understanding form in music, figured bass, notation, rhythm, etc., and how it all works together.

Sight Reading -- The ability to read a piece of written sheet music at sight and transfer that knowledge to the keyboard.

Rhythm -- The ability to understand meter and time signatures and note values; later the ability to recognize different rhythm patterns such as sambas,
swing, mambo, bossa nova, and many more.

Styles -- The ability to add styles such as Alberti Bass, Country-Western, jazz, gospel, etc. to songs.

Runs & Fills -- The ability to add broken chords of various kinds as fillers; straddles, waterfalls, tremelo-fired runs, echos, counter-melodies, etc.

Transposition -- The ability to play a song in a different key than it was originally written.

Modulation -- The ability to move from one key to another smoothly.

Accompanying -- The knowledge of how to "wrap chords" around a soloist so that the soloist feels supported.

Repertoire -- Creating a list of songs one can play at a moments notice without reference to the written music.

Improvisation -- The ability to make up music as you go along.

Arranging -- The ability to put your own special interpretaion on a song by playing it in your own way.

Pedaling -- The ability to pedal judiciously so that your playing is smooth but not muddled.

Dynamics -- The skill of playing at different levels of volume so that the song carries interest.

Feeling & emotion -- The ability to plug-in your own feelings into a song so that the listener feels what you feel.

This is not an exhaustive list by any means, but it's a start. So as you play and practice, think about each of these areas individually, and focus on improving them one at a time.