Think general rule of thumb is you want to have it slip for 2 feet then bite after you punch the throttle. There are a few useful ids on youtube like this one.
Forward to 6 Mins to the demo
http://www.youtube.com/watch?v=YW7can6WjRw
But think that is a general rule of thumb, but people have there own ways some set it on the looser side.. and vies versa..