Second the above advice, but to add some flavor:
1. Always know how fast you plan to take a turn; meaning, set your speed before you enter the turn. The Spyder spoils us with its ability to brake in a turn FAR more than a motorcycle, but just because we can get away with it doesn't mean we should, because of my next bit of advice:
2. The faster you take a turn, the farther into the turn you need to lean. Meaning, if you know how fast you intend to take a turn, you then know how far you'll want to shift to the inside BEFORE you enter the turn.
For example, my best and worst case curves on a Spyder:
BEST: Riding along at 45, entering a twistie with visibility all the way through. Based on experience of the type of curve, figure I need to slow down to 30 mph. I do this before I enter the turn, while simultaneously shifting my weight to the inside.
If I'm feeling adventurous and want to take the turn more aggressively, I shift my weight even further, up to and including a complete lifting of my butt off the seat, repositioning it on the inside edge of my seat, leaning my core to the inside and forward but keeping my helmet/eyes level with the turn, holding onto both grips, using my knee to grip the tank, and pushing off the outside peg with my boot. Once I pass the apex of the turn, I shift back to center and accelerate, or if there is another twistie ahead, I shift before I enter that one, i.e. in an S-curve I might shift from all the way left to all the way right without stopping in the middle of my seat. (You can more easily ride straight for a little bit from off-center than ride hot through a curve sitting square in the middle of your seat).
WORST: Riding along at 45, entering a twistie with poor visibility through the curve, I don't slow down much, and I only do a "lazy shift", i.e. just a slight lean of my upper body into the turn. Halfway through the turn, I realize I'm too hot/encounter an obstacle/encounter traffic/discover a decreasing-radius turn. I then have to brake, leading to an ugly and uncomfortable dogleg through the turn, AND likely shift my body over more to compensate for the curve.
I admit, I've done this more than once, and immediately berated myself for not properly setting myself up for the turn. But it's a lesson learned.
If you're driving the Spyder lazy through big sweepers or slow turns, you can get away with very little lean. If you're riding aggressively, you need to increase your lean dramatically.
Personally, I don't even like using the word "lean", which makes one think of how you lean on a motorcycle. Even a dramatic lean atop the Spyder doesn't shift the weight all that much-- I find it FAR MORE useful to do the "lift butt, shift butt" maneuver where I sit on the inside edge of the seat. If you practice both styles, you'll notice a big difference in how fast and easily you can take the turn.
For the record, if I lean only, there are times I set off the Nanny in a curve. If I shift my butt, I don't think I've set the Nanny off once, even in fast curves.
Bottom line: look ahead where you're going, don't outride your sight distance, prepare for the curves BEFORE you enter them (including setting your speed and shifting your weight), and always be prepared for a decreasing-radius curve (if you've already shifted your weight at the beginning of the curve, if you're surprised you'll find it easier to shift *just a little bit more* versus having to move over from center line to react to a surprise).
Anyway... that's what works for me. The fun is figuring out what works for you!
