So, I have tried to do something different, and having done this in less than 4 hours I would recommend this as an exercise.
Find a piece of music that you like, and essentially us the STRUCTURE as a skeleton, while of course being sympathetic to the style and manner of your chosen work. The rationale with this exercise is that you need not worry about structure for it is already laid out for you. You only need to make the music.
Here is the outline
Primary theme X2: I/IV followed by prinner
Re-transitional overture leading to converging cadence (the former meaning a common device where the a sentence forms around the tonic triad but on the 5th degree, the key shifts to the dominant. It was commonly used to mislead the listener.
Secondary theme:Quiescenza (osculation between the dominant and subdominant) followed by a prinner. This is then repeated an octave down.
End of A section: Quiescenza
Primary theme X2 (V): I/IV followed by prinner
Development centered on reoccurring motifs and circle of 5ths, perfect cadence in G Minor
Adapted primary theme in G Minor
Proceeds to C Minor-F Minor, and returns to home key through Neapolitan 6th (not uncommon!) before pause on a converging cadence (back to dominant)
Then all repeated from Secondary theme but in Tonic Key.
Straightforward stuff but effective!
Second movement to follow shortly.
FYI - This based on JC Bach's OP 5 no 1.