Most pieces of music are written in set musical and technical patterns, and from these patterns we can extract exercises and studies to be practiced as separate entities. For instance, the Waltz on page 66 is essentially using just two chords, tonic C and dom.7 G7 (shown above notation) and groups of right hand arpeggios. These elements which occur repeatedly can be considered common denominators, and should be practiced separately before attempting to put the piece together. Note that the G7 is not exactly as presented on page 63# but uses the notes essential to this chord (see page 64 "Chord Voicing") which, regardless of their pitch (highness or lowness) used together can only constitute a G7 chord.
Firstly practice the left hand changes as block chords (all notes played together) by repeating the C, G7, C etc., until it can be achieved with little problem (see Ex.1).
Next, practice the right hand arpeggios separately using C or G7, or open strings (as seen in Ex.2).
By concentrating on each hand individually, it will make it easier to combine both hands as written, because each will be working almost automatically.
This practice method should be used at all levels of playing.