Find the phrases, where they begin and end. Use more bow speed when playing Bach. Strength at the frog comes from arm weight, not muscle power. Strength at the tip comes from raising the elbow. Sit such that one has mobility, with a wide stance and feet forward.
Contrary motion helps with the bow too.
Use feet for power too. Clean up the bow changes with finger flexibility. Talent isn't enough. You must formulate musical ideas too. Debussy Sonata A great starting point is to be literal with the score.