I have tried three basic techniques:
- One-handed underhand toss
- Two-handed underhand toss
- The shotput toss
In my experience the two-handed toss is more reliable than the one-handed. I have also learned that the shorter the distance the ball has to travel, the less opportunity for it to get "off course." So now I do all my tosses with the shotput. It cuts about three feet of vertical travel off the toss and seems to be the most reliable method I've tried.
BTW, I've seen Scott Thornley (MWC mens official) stand on the edge of the jump circle and toss it so that it drops down over the players. Interesting, even cutting edge, but hardly likely to fly in HS circles