This maybe just me, but I like to toss the ball a bit higher. It's counter-intuitive, but one of the main things that impedes my spin production is tensing up and ultimately being anxious about all the variables: wrist action, height of contact, place of contact and angle of contact. If I toss the ball higher, I can consciously relax and focus on delicately catching the ball, not forcing it over the net. The timing is more difficult as the ball is moving faster (and the playing area's light might annoy you), but it allows time for all your muscles to relax, before the point of contact. At that point, get your foot down and explode backwards into ready position. Serving should be relaxed, purposeful and graceful. I got into a bad habit of not getting into ready position because I'd spend hours serving again and again from the same position without ever practicing the move into ready position. But in general, I think it's the mark of a passionate TT player to hone service.