General advice:

The Piano Game is an open learning system; you can start anywhere, driven by your own desire to play particular music. However, use common sense. Really hard music may wear you down and give you a feeling of failure, while really easy stuff will still be challenging to move through all the Game levels. Strike a balance and shift material frequently.

Technique will come from playing the music itself but you can also learn scales and arpeggios in the technical library.