In your Sonatina Analysis. (First Step) egin with harmonic reduction — do not reduce the melody; instead write it in its entirety, with rhythm, with steps pointed upward, on horizontal staff paper. Write most of the other notes without stems or rhythmic information, but placing them in approximately their relationship to the melody in time.
Complete a harmonic analysis sufficient to comprehend prolongational, intermediate, and cadential harmony and melody. It’s often clarifying to begin with cadences. You do not need to label these three kinds of harmony; instead, make them clear by using two stems each for melody (stems upward) and harmony (stems downward from the bass) to indicate your sense of the the “essential” cadence, one stem each (for melody and harmony) to indicate a prolongational note that seems to cohere to the cadence. Indicate intermediate harmony with a slurred bass note showing “pre-cadential” harmony; usually a predominate chord leading to the dominant. Intermediate harmony is not stemmed, but is marked “PD”.
That’s all that’s required of you. But make note of any elaborations you see, that might help you in the next step, to identify the structure that connects the three kinds of harmonic and melodic information. Remember, each elaboration you see should be an elaboration of something, i.e. whether it’s a neighbor note, a voice exchange, or an unfolding, the elaboration should be connected to a note that, on some level of structure, harmonically supported and strongly related to one of the three kinds of harmony.