I think relaxation and patience are all you need to learn Jeux D'eau (by Ravel, which is what I referred to before). For the first three weeks of learning it, I could make neither head nor tail of it, and all of a sudden one day the first 6 pages were memorized - another 2 or 3 weeks and I had the whole thing from memory.
I think memorizing it is particularly important since it's harder (for me, at least) to sightread than earlier genres (like Chopin or Beethoven). A lot of patterns written into Jeux D'eau won't be very apparent until you've taken a good deal of time to sit down and really
think about the music - this makes memorizing it a great deal easier. Another helpful method in memorizing this piece is to treat it contrapuntally, rather than harmonically. Follow each voice seperately in your mind (for example, in the difficult rhythm section leading up to the glissando - the bass notes in the LH are a melody, the top of the RH is a melody, and the arpeggios have their own patterns that can be made sense of with a little thought) and memorizing will become a matter of a few short weeks or even days, depending on prior experience.
Concurrent with memorizing the notes should be memorizing good fingering. There are a few passages (a page in the LH right after the glissando, for example) that will probably be very awkward, and starting off with a less-than-ideal fingering will really get you in trouble when you start picking up the tempo. This is the highest obstacle when it comes to learning the piece, in my opinion, since it can be very discouraging to have to change fingerings two or three or four times (as I had to do!

) before settling on something that's comfortable at the tempo of choice. If you haven't had much experience with more advanced repertoire, it would be good to discuss fingerings with a teacher or more advanced pianist at trouble spots.
Once the piece is in memory and good fingerings are chosen, the hard work's pretty much over. Just play slowly, (I am a big advocate of the metronome) and RELAXED and eventually things will just fall into place. For passages that you feel are truly above your technique (that fast whole-tone scale in the beginning, the RH arpeggios in the middle and at the end, etc), you may need to set aside a lot of time to raise these spots to the point where they are on par with the rest of the piece. Even for these, though, I'd say it's only a matter of time (possibly a long time...

) before you'll be hearing "oohs" and "aahs" from your audiences.
Lastly, if there are spots you just don't know how to approach, you can PM me and I'll be happy to go into greater detail.

Good luck!
- M