This variation uses A fast bowstroke where the hair stays in contact with the string while the stick bounces. with four bows per note, which allows time to make sure our finger fall and finger lift are precise and that our string crossing action is smooth. Work towards a continuous rolling of the arm (round bow) for the string crossings.
Changing from a crescendo to soft subito can be challenging in sautillé stroke. Try changing hair inclination (flatter for loud and more on the side for soft). Try varying the sautillé action (more of a forearm sautillé when playing loudly and more of a hand action when playing softly) .
Think about the challenges for coordination and how the left hand needs to be ready in place (finger before bow) before the bow articulates the note. This is especially important when playing sautillé.
Think about where to hold fingers down (for instance the 1st finger in bar 8) and how to practice the many double stop fifths. For the fifths you can either place the left-hand fingers together, or use the left arm to roll the finger across to the higher string (for instance the C going to the G in bars 1 and 13).