Minimise hand movement, especially vertical. The hands should always be close to the keyboard. Too much 'in and out' movement when going between white and black notes is also to be avoided. If your wrist starts to stress, stop. There is no point practicing octaves unless your wrists are relaxed. In double octave passages, the counter-intuitive (if you are right-handed!) realisation that the left hand is the guide, not the right, usually makes them a lot easier. Finally, the difficulty with the Liszt sonata closing octaves is that they are somewhat irregular, unlike eg Chopin 25/10. Consequently, if you were looking for a good etude I would suggest Alkan 35/5, Allegro barbaro.