Sampras and Federer was known for disguising their serves by using the same toss for different types of serve. So, is this true for this second serve as well? On this second serve, Federer uses the kick serve, but to hit a kick serve, you have to toss the ball behind you. so how does he do it without giving away that he's going to hit a kick? I've tried that too, but i can only get more kick out of the ball if i toss the ball behind me....
It's just one more thing that can give the pros an advantage. It's also one of those things that most pros can do, but very few players below 4.5 can.
I also don't think the disguise matters all that much at or below the 4.5 level. IF you have an effective kick serve, most 4.5s will have trouble with it whether they know it's coming or not. However, I have found this method of disguise to work: Try tossing in the same spot as your flat or slice serve, and simply let the ball drop a bit lower. If you can keep your shoulders from opening up, and learn to brush up the back of the ball (make sure you still extend fully even though you're catching the ball lower), then you can hit a pretty decent kick. Still, though, for those massive kicks out wide in the Ad court, I place my toss in the traditional place...which is directly over my head and slightly into the court.
For the second serve it's no secret that a topspin serve is coming, even at the pro level. However, my TOPSPIN serve is different from my KICK, or twist, serve. The kick serve is a first serve weapon that breaks to the left of the bounce from the perspective of the receiver (righty). The topspin serve simply has neutral topspin, or maybe a slight slice depending on placement in the service box (for instance, wide to the deuce court). I most definitely use a different toss on the second serve.