Many basic challenges of coordination are due to a late left-hand finger action. The finger may not be set up ready to play before the bowstroke happens. This creates many problems, one of which can be a hesitant bowing action.
To develop good 'finger before bow' technique, use stopped staccato bowstrokes within a slur, and put the finger down with a deliberate action in the break between bowstrokes.
At the slower tempo feel two beats on each note and have the new finger go down or lift on every 2nd beat - a whole beat ahead of the bow.
Another way to improve left-hand readiness is to play sautillé.
Facility - Use Sautillé to Develop Facility
Resources - Repertoire
- School of Violin-Technics Book 1 by Henry Schradieck