Start slow, and work out the fingering for yourself. If your really having trouble buy the Alfred Piano edition, that has SOME fingering. By the way, I tried to learn a bit of Moonlight Sonata 3, and I can easily play the first 20 or so measures. However I realized I get a little tired after that so I`d have to work really hard to build my stamina to play the whole freakin thing. (I`m better now but I`ve put Moonlight SOnata away for the time being)What makes it really hard is it`s length (like 7 minutes of that stuff). Even though it`s fast, you can practice that to get good at it. So have fun, and work hard to build up your endurance.
28th April, 2017