Composing Classical Piece, Form Recommendations

Hi, I am new here. 

I have studied theory of music on a Music Academy and since back then I am composing mainly modern pop mainstream music.

I want to apply my knowledge of classical Harmony, Counterpoint, Forms and Orchestration into composing classical piece so I am a bit uncertain where to start. 

It may be a piece for piano but not Sonata because it is complex for beginning. Any other form of piano composition you could recommend? 

Also, what is a good book on teaching you composition if you already have a good grasp on Harmony, Counterpoint and Forms?

Thanks in advance, happy to be here. 

1 hour ago, ilv said:

Rondo form
Theme and Variations
Large ABA structure (e.g Minuet/Scherzo and Trio)
Free form (e.g bagatelle, prelude)

 

Thank you ilv, I was thinking about Minuet also, but you gave me a nice suggestions to pick from.