I'm interested in knowing what resource you are using to try and learn the classic pass Sidekick. I learned it from multiple resources myself, including Card College, that Ellusionist DVD Ninja and other various resources.
You could use all the misdirection in the world, but there will still be that one spectator that won't take his or her eyes off of your hands. Ideally, with years of practice you will be able to have someone burn your hands and still pull it off.
The only advice that I could really give you when trying to perform any kind of shift, is simply that finger positioning is everything. For instance, when doing the classic pass make sure that your covering hand has no gaps between the fingers when the pass is executed. Other than that, mirror practice is absolutely essential to learn the timing and angles for any pass.
Sincerely,
David