The three key components of every shot, Angle, Speed, and Spin apply to masse, just like any other shot. Your variables are the angle of cue elevation, the spin applied depending on how far from center you strike the cue ball, and the speed of your stroke.
In order to learn to control your masse, you must first be able to consisenttly control each variable. Once you can do that, you maintain two of them, and observe the different results when you change the third variable. For example, keep your stroke speed and spin the same and change the elevation of the butt. Or maintain the same elevation and speed, but change the contact point. You will learn how changing each of these variables will alter the path of the cue ball.
Steve