Golfers Elbow: Hold the dumbbell in the palm, thumb against fingers. Let the weight slowly roll out to the fingertips and lower slowly. At the bottom of the movement, use the other hand to pick the weight up and return it to the palm. Do sets of 10 or 12, and a final set until failure. (weight not shown for clarity, use 10-20 lb dumbbell)
Tennis Elbow: For this exercise, use a rubber “Flexbar” made by TheraBand. What the picture doesn’t show is that after you finish the motions shown, you release the bar with the noninvolved hand and return to the first step, Figure 1A, and repeat. You can see the full sequence in this video.