Piano Forum

I'm just an amateur; others may give you better answers.

Trills - I'd suggest practicing them out of context. You are aiming for a couple of things. The right balance between finger action and forearm rotation, and that depends on exactly which fingers you are using and whether you are trilling white to white, white to black or black to white, or black to black. Also you want to lift your fingers as little as possible, just enough so that the key will sound the next time you play it. It's easy enough to work out an exercise where you trill major and minor seconds in all combinations of fingers and on all combinations of white and black keys. Don't think about the Mozart sonata just concentrate on how things feel. To me it feels like my fingers are riding on the keys using not so much force and without much effort.

In the short run you can just go for a measured trill, even one in 16ths. Not ideal, but better than tensing up your hand to try to trill faster than your technique will let you at the moment.

For the turns, I find my problem to be sticky fingers - the limiting step is getting the fingers off the keys fast enough. To help with that, I practice turns very slowly using a flicking finger staccato. After I've done that for a while I go back to tempo and try to maintain that feeling of a quick release of each note.

You can also try looking up Josh Wright, Danae Dorken, and Nahren Sol in youtube. They all have instructional videos on trills, though they do not say exactly the same things (e.g. Danae is totally against using forearm rotation, while Josh thinks it necessary). You can listen to them all and experiment.