I didn't play La Campanella so i can say to you nothing.
About Revolutionary:
First, practice the left hand alone coz it is an Etude for the left hand after all. Feel the accents every quarter note and give great care to correct fingering.
You cannot play it at speed without good fingering, so don't try to increase your practice speed without being so confident with your fingering.
Also, take care of the middle part ( after the stretto and the chromatic run ). The left hand is so tricky and so hard to get it right there. Practice it like a hundred times everyday HS.
Last but not least, don't neglect the musical aspects of this Etude. Although it is a truly Revolutionary Etude, but it needs great care to bring out what Chopin meant of it.