Did it ever cross your mind that "sound better" has as many different meanings as there are different people?
If you're new to mixing, don't ask anybody "just where to click". Listen to tracks that you like and try to figure out how to make your own sound similar.
Btw, you'r saying most of your music is MIDI based. There is no way to make a MIDI piano sound right, at lesast not to people who actually know the sound of a real piano.
> Any ideas or tricks from you more experienced Pros on how to make the
> piano/vocal duet sound better would be much appreciated.