Paul, I'm not gonna tell you I know a lot about setups, but I will tell you that I know a lot more than I did 3 years ago. All I did was change one thing at a time and take the car for a spin. Do this over and over on a track you know like the back of your hand.
Generally, if your car is oversteering, tighten/stiffen up the front and/or loosen/soften up the rear. Reverse that for understeer. Different combinations of sway bars, dampers, and springs, can be used to stiffen or loosen. The same combo doesn't work for all the cars. For example, one car might like stiff dampers and springs but a soft bar, while the other will be the opposite case.
Just mess around and see what everything does.