I'm not sure if anyone self-taught can ever learn or perform advanced repertoire at any sort of acceptable level. If you don't have a teacher to show you "how" to approach these pieces, "how" to expand and control your technique, you may never gain the technique needed.
I can make suggestions like Czerny, Pischna, Dohnanyi, Hanon but if you don't have someone with experience guiding you through learning these studies you won't progress, or worse, you will injure yourself. Even something as seemingly simple as scales and arpeggios should be learned with a good teacher.
Have you ever considered getting a teacher?
All of that being said, look at the Liszt Consolation in D-flat.