Hey Caroll. I actually have a detailed chapter in my Fiddle for Dummies book regarding “bow anticipation,” which is an important part of how to get a continual tone. If you don’t have the book, I suggest checking out a few of these videos which will explain and drill the concept of keeping the bow moving continually.
Motion of the Index Finger – Good for understanding how the index continually should be moving the bow.
The Index Drill – Good for building muscle memory with the index finger.
The Wall Index Drill – Good for restricting other muscles from getting in the way of smooth transitioning.
Let me know if you have any questions!