How do you memorise? bar by bar? Phrase? Can you pick it up from any point if you break down?

Do you memorise hands separately or together?

Like to know your methods.

I analyse until I understand the harmonic structure and then learn the chord progression. I only have to hear the melody to be able to remember that - but the left hand needs more work.

I have four things that I need to have, all together

1. How it sounds- usually melody, sometimes harmony

2. How it feels- muscle memory

3. How it looks on the page- I actually try to remember what the score looks like. This also helps me not get lost because I am following along in my head

4. How it is put together- musical analysis. This is especially good for things like Mozart sonatas which have a structure but where the exposition and recapitulation are almost the same except for crucial bars with a key change.

The final thing I add to this is the concept of "checkpoints". I keep track of where I am in the piece and where the last checkpoint was. This means that if I have a memory lapse I have a higher chance of resuming from somewhere. This has saved me before.

I've only just started learning how to memorise on piano, so this isn't based on lots of personal experience, but is the technique my teacher has suggested:

1) Select a suitably short phrase (it may be as short as a single bar, if there are lots of notes in it!)

2) Play it WITH the music until you have managed to play it 100% accurately 5 times IN SUCCESSION. The latter part is the killer - if you make a mistake, the counter re-sets to 0.

3) Take away the music. See if you can play it once from memory 100% accurately. If not, go back to step 2. If you can, play it 5 times from memory, 100% accurately and in succession. As with step 2, any mistakes re-set the counter.

4) Replace the music. Play it at least once more with the music in front of you, noting how your perception of the music may have changed.

5) Repeat for the next phrase.

6) Then try joining the two together.

It's slow and laborious, but I would have said before trying it that I would never have been able to memorise anything, and I have now managed (in the past couple of weeks) to memorise all bar the final section [which I can't actually play ] of a Mozart rondo, plus the initial subjects of a Chopin waltz and some Debussy. I have also become aware of how much I rely (subconsciously) on "sight-reading" a piece rather than thoroughly learning what notes I have to play and when, which has given me a clue as to why I struggle when under pressure (eg in an exam or performance situation, or when trying to play at speed).

It's interesting how many parents express concern that their child is playing from memory. They think it's not doing it properly if he's not looking at the music.

On the other hand I do have to persuade some children to open the book and have the music in front of them "just in case". Ever since I saw a little boy break down in tears at a high scorers' concert when playing a grade 1` lullaby from memory I have never allowed a child to perform without at least having the music open, even if they are playing "by heart"

If one gets used to playing from memory, having the score open is as likely to be a distraction as a help, at least from my experience. I have on a couple of occasions had huge memory slips in concert, and the only way I could recover was to restart from somewhere else and let my fingers work automatically for a brief time until I had fully regained concentration. Searching through the score to find my place (because I wouldn't know where I was on the page, having been playing from memory) would have made things feel even more unnatural and made it more difficult to focus. Right before my DipABRSM retake I panicked about memory and asked my teacher if I could somehow use the music during the exam. My memory of the programme had been secure for ages, but I was worried about unexpected behavior in a performance situation like you describe. She told me that it probably wouldn't help, and I soon realized she was right. Of course it might not be the same for everyone.

French children are not allowed to play from music in a concert (it's a sign that you haven;t sufficiently learnt the piece to transcend the actual written notes and turn it into 'real music').
And anyone bursting into tears is considered just fine - it will teach them next time to darn well learn it properly !!!
I think, for them, it's simply a question of repetition and what's the 'norm' - that's the way you're taught from day one.
However, one G7-ish pupil has just spent 6 months at the conservatoire taking specific 'playing from memory' lessons to hone up his skills - but I don;t quite know what was taught so can't help.
All I know is that i can play every single G1 - G4 piece that any child has played this year - that's purely repetition from listening !!!!

Both, but phrases are more natural. Sometimes i am reduced to learning two notes at a time.

Some pieces yes, some no.

Depends on the difficulty of the piece, and how long I have available, but learning hands separate AND hands together leads to more security.
By the time a piece is securely memorized I could write out the score from memory, or play it over mentally without relying on "muscle memory".

Along the way to that level of competence I rely on gradually more solid "muscle memory" and alongside it become familiar with the musical structure and ideas. Aural memory also tells me when I am getting it right, but if it tells me that I have made a mistake I take note, figure out why, and practice the offending bit until it is secure. [Of course in performance it is not possible to correct a mistake, so one just has to plough ahead, get back on track, and hope the damage was minimal]. Aural memory is rarely of much help in recalling the right notes to play quickly enough to actually play them, although that might be possible for for someone with a very strong association between particular pitches and the notes of the keyboard - which means perfect pitch allied to a good feel for the geography of the keyboard. But even then, it could easily lead to an awkward fingering, so there is no substitute for a well-grooved set of conditioned reflexes.

Also useful are: settling on a fixed fingering as early as possible (but please do change it if it turns out not to work) learning each melodic line separately in contrapuntal sections, learning the harmonic progressions as block chords, listening carefully to each separate harmony and change of harmony, observing suspensions and passing notes, figuring out how modulations are achieved, finding thematic connections and variations throughout the music, playing the RH part with the LH and vice versa (this is not always possible, but when it is, it can be done with crossed hands, or with RH part transposed to the bass and LH part to the treble), transposing to other keys (a real mental challenge, and very hard work!), playing on the surface of the keys (imagining the sound), mental practice (imagine both movements and sounds), singing the melody, singing the bass, singing the inner voices (a private practice space helps), recording and listening back, overemphasising dynamics, speed changes, and special effects (in practice only - to better remember them - they must be toned doen for performance) and generally playing about inventively.

I should add that the quality and intensity of concentration make a big difference, and that it is far easier (or at least is seems so) to learn a piece that you adore, than one that you are learning because it has been prescribed for you by someone else (teacher, instruction book, impressario).

If this sounds like a lot of work, it is! Some lucky people memorize quickly and effortlessly, but for most of us it takes a long time to come to know a piece so well that we feel entirely confident about performing it without the score. It is a common failing to underestimate (perhaps I should say MASSIVELY underestimate) how long it takes to fully master a piece of music. We would all like to be able to learn a sonata in a cope of days, and have the huge reperoires of an Idl Biret or Lang Lang, but wishful thinking cannot change reality.