Boy Paganini is a beautiful piece focusing on expression and dynamics. Without expression and dynamics, this piece would be very boring indeed. Therefore, the majority of your time needs to be spent learning the dynamics and infusing interest into the piece.
Vibrato is a key factor in this piece. Make sure to use a lot, but be mindful of how you use it in order to get the most impact from the piece.
Spend time working on adding crescendos and decrescendos within the dynamic range marked. Add accents to the notes, and lift the bow for added amounts of expression. When the phrases repeat themselves, try to make each one express differently by using different dynamics.
In the second part of this piece, our focus will be on a strong driving rhythm. This is different than part one, where we are more slow and expressive.
The third part is simply a combination of both the first and second parts.