Re: Discovering the Piano again
Bartok's 'Mikrokosmos' is a very good standard text. There are a number of books, ranging from the first which is basic up to and including concert-standard and beyond.
You might also benefit from looking at some of the other Piano etudes. Depending on what technique you're trying to develop, different etudes may be appropriate. I'm not a Pianist (my brother is - and very much so) so I can't be specific in my recommendations but somebody will know.