After years of tennis I finally discovered how to properly toss the ball! I was doing something wrong from the beginning, meaning that when I was bouncing the ball onto the ground I was kind of flicking it with the top of my fingers and then rushing a bit when I was throwing into the air because my tossing arm was somehow a bit tensioned and stiff. But recently I adopted a more relaxed service motion, always bouncing the ball 3 times very very sloooowly, most important of all, with THE TOSSING ARM COMPLETELY RELAXED, with no tensioning whatsoever. Then, I lift the untensioned arm as a LEVER, straight arm, again with no rushing, slowly lifting the arm and slowly releasing the ball which was on the tip of my fingers when it reaches the same plane with my shoulder/head. The conclusion for me? The tossing arm must be relaxed all the time. I also discovered that bouncing the ball less than 3 times makes me rush my serving motion. Previously I was bouncing it 2 times, but with 3 bounces I find that I started to "feel" the ball much better before I toss it. Result is a more reliable toss serve, with the ball spinning less into the air and a much more consistency overall. I think the secret is that the lever that lifts the ball must be totally relaxed. Hope that helps.