Work out the best point of contact for the sound that you want.
A slow bow speed with the point of contact near the bridge gives you a strong sound. As you get further away from the bridge, towards the fingerboard, you need to move the bow faster to keep a ringing sound. Have enough bow friction to make each point of contact work.
Begin by imagining the kind of sound you want to make. Try creating a picture in your mind of a place or colour to go with each new passage.
This excerpt is from "Meditation from Thais" by Jules Massenet.