This song is very well-known. It is Mozart’s and it is tricky. For a successful execution of the piece is essential to respect the fingering. Especially in some sections such as the 5-6 beats with the right hand or the 1-2 beats with the left hand. A wrong fingering could really compromise the execution.
Many beginners are skeptical about following the fingering.
Actually, it is the most important thing to respect in a score. Only with a bit of time and with experience, you will notice that the designated fingering is the safest and most comfortable, in short, the most suitable to our hand (none in the world has hands of equal length and thickness, so only in some very rare cases, it is advisable to change the fingering).
The respect of the phrasing is always important, but in this piece is not as essential.
The left hand could play almost always legato with the exception of certain points, while the right hand plays legato only on beats n° 3, 7, 8, 12 (on the twelfth, there is an appoggiatura),15, 16, 19, 20, 23, 24.
In short, the right hand must legato only when the octaves are played.
In this piece, the dynamic ranges from “p“(piano) to “ff“(fortissimo), so you must regulate it well. If nothing else, the piece begins with the “mezzoforte”, that means you have to play with average strength.
Starting with “mf” is really a benefit because that way, you can adjust the dynamic beat after beat, until you get the mechanism of the piece. On the beats n° 17-18, there is a “crescendo” that goes from f to ff , then back to mf.
Listen to the performance to get an idea of the right dynamic to use.