With all the 40 variations we need to make sure our left hand is helping the bowing as much as possible.
In this variation, since most bars use the interval of a third, practice the intonation of the thirds.
Especially when shifting it is tempting to just think of shifting to the first note in the new position. Practicing backwards broken 3rds is good for developing the whole hand position so that both fingers are ready. This applies whether shifting or not. For example, in bar 1 tune the A (4th finger) then the F# (2nd finger). In bar 2 tune the B and then the G.
Teach your hand the degree of the interval (minor or major 3rd) by practising all the minor 3rds in a row (bars 1, 3, 5, 7 and 9). Then practice the major 3rds in a row.
Plan your finger fall to assist smooth string crossing. For instance in bar 11 place the 2nd and 3rd notes together as a 5th and in bar 12 place the 2nd and 3rd notes together as a 5th.
As always when playing legato (in the string) followed by a lifted stroke (in this case up bow A slow to moderate speed bouncing stroke.) think about the angle of your bow hair. Here you can use a flatter hair for the legato 1st beats of the bar and roll to the side of the hair for the lifted up bows.