Piano Forum

With Bach's fugues, my teacher and I always write all the fingerings in (yes, every note).  That way, we can pick up from any place without our fingers getting tangled.  Then we memorize each voice separately after highlighting them in different colors.  My teacher says their memorized when it becomes "boring" as is boringly easy to play them without the music.  (If you just highlight the middle one (s), it automatically separates the top and bottom).  Oh, we also highlight the subject/answer entries as well, so it's easy to find and bring out. 

After the ground work is done, and the voices memorized separately (with the finger you would use if you were playing the other voices at the same time - so the middle voices are often played with mainly thumbs and 2nd fingers!), then after that, with the music, we learn all the various voice combinations - 1 and 2, 1 and 3, 1 and 4 (if applicable), 2 and 3, ect.  The memory of the individual voices is to be still maintained while doing this. 

Then we write a number (aka. memory point) on every other bar.  Then we memorize it so, she can call a number, and I will start from that place without the music.  Ultimately, you can play the piece through by memory, and skip every other bar.  And if you lose your place you can pick up from every other bar, as well.  We make sure we can still play the voices separately from memory, and use the music to do voice pairs still, as well.  It's useless to do the first steps if you aren't going to maintain them.

Afterwards, we add shaping and such. 

1. highlight/finger numbers
2. voices separate - memorize (or at the very, very least, learn them like this with the music, but memorizing is better)
3. voice pairs with the music
4. all together with memory points
5. shaping

It's brutal, but it works well!  I didn't believe it until I tried it and saw/heard/experienced the difference.

Some benefits:

1. You don't need to be paranoid about losing your place, or only having muscle/finger memory.
2.  The first steps make memorizing it as a whole much easier.
3.  Your playing will sound so much more horizontal rather than vertical by familiarizing yourself thoroughly with the "lines" and their various combinations before putting it together.
4.  It makes the individual voices stick out more.  I actually learned 2 fugues just straight up like a regular pieces and did fine with them (thankfully never lost my place in performance, though every performance was an anxiety attack).  But this one I did memorized voices separately first (that's the most pain staking step because it's seems like it takes forever, but it's worth it and goes quicker after it's over), and I also practiced the voices in combinations.  Then I played the first page for my mom, who doesn't play piano, and she remarked that, that was a "different way of playing."  When I questioned her about it, she said she could hear all different voices playing together.  I'd played fugues for her before, but this is the first one that I did this way, and the first one that got that comment.  I hadn't even put any shaping into it yet, but was just playing the notes all the same volume/dynamic, and she still picked up on it.  That was actually my prelude (we did it the same way as it is "fugue like" in character. 
5.  a trained ear can pick up on these extras (especially helpful when playing in an audition or for an examiner)
6.  you really feel like you understand the work


And also, a good tip I was given when playing the voices in pairs - when you have the subject and other material (two lines), happening in the same hand, and you're trying to make the subject louder than the other half of your hand, practice "ghosting" the other notes (not actually pressing them down, but still aligning your fingers over them as if you were going to play them along with the other notes/subject).  That way, when you do add them quietly in, it will be so much easier to hear the subject, and so much easier to not play the other stuff too loud.  I didn't do this last time and got nailed on my exam.  They said the inner voice subjects were brought out, but not as much as they could be.  This time, I'm going to practice it ghosting so I don't lose marks!