They are bewildering because they can produce the same effect when pushed to either extreme (soft, hard), and if you get the pairs mixed up, you sometimes really have no idea where to go.
Tweaking the dampers should be one of the last things you do when setting up the car. Take care of the gearing, wings, brake balance and temperature and other tidbits, and pay special attention to differential locks, because they have a lot to say about understeer and oversteer and affect the car into, out of and through corners. Camber and pressure will have to be tweaked several times as each change of the setup will affect tyres. Caster and AntiRoll Bars can completely change the way the front wheels behave while cornering. All this can create problems for damper settings and you could lose your mind trying to fix everything that went wrong at once.
For example if you had the brakes setup wrong, and you fixed it, your car would now have much better deceleration, and that would cause weight transfer to be different under braking and corner entry, so the dampers would need adjusting. You can see why it's better to take care of all things that demand damper adjustments before you try to find ideal damper settings.
I prefer my dampers very stiff and the suspension average-below average stiffnes while i'm working on a setup. Then when i get the car to behave the way i like, i fine tune the dampers. Based on experience i might even "guess" where the dampers should be, but until the rest of the car is fit for the track and handleing to my liking, i won't adjust the dampers.
Instead of looking at the suspension histograms...
- take a look at ride height to see if the car is bottoming out
If it is, raise ride height or stiffen the suspension.
If it never comes close, lower ride height to lower the center of gravity
- keep checking the tyre temperatures
Inside should be 5-7 degrees higher than outside (front), or 3-5 degrees (rear)
Keep adjusting camber untill you get those temperatures. (keep in mind that one side of the car works harder because the number of left and right handed corners isn't equal)
Middle temp should be between inside and outside. That indicates correct pressure. Just remember that when you adjust camber, you will probably have to adjust pressure as well.
On tracks with long straights, pressure can be a bitch to set right. You have to focus on the turns where the car leans to one side, and check the temperatures there, not the straights.
Having tryes that correctly grip the surface is more important than most other settings.
I also suggest you check your differential before you go for dampers.
- a low cost lock allows the rear wheels to have a greater difference in speed (when no throttle is applied), which greatly helps the car turn into corners, but it can can cause massive oversteer if the car turns in too easily and the rear tyres loose grip. High coast lock settings doesn't allow such a difference in wheelspeed so the car doesn't turn in so well but also doesn't spin so easily. A badly set coast lock can develop oversteer or understeer on an otherwise neutral car.
- low power lock also allows a greater difference in wheelspeed but this time only when under power (throttle is applied). This is bad because some of the power is wasted and the car is not so fast when exiting corners, but if there is no wheelspeed difference (100% power lock), there is no cornering benefit while the car is still exiting the corner. In fact the car may develop massive understeer and force you to get on the throttle much later through a corner.
To see what i mean, try a 0% coast and 100% power lock.
- low preload makes the effects of coast and power lock more pronounced. High preload subdues the effects of coast and power lock. It's not quite that simple but that's the jist of it.
I hope you see how differential can affect everything from lap times, corner entry/exit and even your driving line.
I apologize for a complicated reply, but i hope it was usefull.