To synthesize what's been written above to capture what works for *me* on my RS:
1. The pattern I tend to use is shift-lean-shift.
Meaning, making sharp *low-speed* turns, it helps to shift your butt to the inside of the turn at least one cheek-width. Then lean forward towards the inside mirror, grip the body with your knees, and push off the outside peg.
During normal riding at speed, I do the same, but I lean instead of shift.
During *faster* riding, I transition back to my low-speed technique: shift my butt *before* I enter the turn, shift my butt out after the turn.
Still, 90% of the time I can get by with leaning versus shifting. But it's important as a Spyder rider to recognize those times when you *really should* shift your weight.
The worst is when you enter a turn too hot and discover you either have to bleed speed in the turn (yay understeer!) or abandon your lean in order to shift your weight to the inside (upsetting the vehicle more than a little bit). That's why when I go into the twisties, I just make sure I'm focused enough on the road to do the shifting versus leaning, and keep myself out of trouble.
2. Technical upgrades help A LOT. As mentioned above, set your suspension to its stiffest and upgrade the sway bar or shocks if you can. Also, changing your seating position can help your handling: risers, aftermarket seats, footboards versus pegs all can contribue to a very different handling Spyder. The stock RS handlebars and pegs make turning lots of fun, but definitely make you concentrate on it. Adding in risers and footboards extended my "leaning" margin by a great amount (good!) but unfortunately made me have to re-learn that point where I transition from leaning to shifting (bad!).
Again, every time you make a major ergonomic change to a Spyder (or any motorcycle) you should take the opportunity to practice how it handles in a safe environment (big parking lots, empty roads at 6 am, etc.).