I found that setting up suspension (in this order) helps me a lot. I primarily drive RWD cars in the A, S and U classes.
Set up the front suspension first. Then go to the rear.
Diff Accel: do this by feel. Start broad and narrow it down. Reduce the diff accel to get the best possible traction. (Note: I've learned the hard way that corner exit depends tremendously on corner entry - if the car isn't turning in and tracking properly on the way in I tend to compensate by over accelerating and trying to "steer" the rear wheels with the power - bad idea, always!)
Rear springs: don't just make them soft - make them as soft as possible while ensuring they don't flash red as you squeeze the accelerator.
Set the tire temps: try to get your tire temps at about 32psi after two or three laps )generally start at around 29psi and drop or raise a psi after viewing the telemtry. Seldom do I have to go more than one psi in either direction.
Set the camber and castor: try to get even temps. It's impossible, but get it to within 4 degrees across outside, middle and inside. If one (inside or outside) is higher then make sure it's the inside of the tire.
Set the bump. If the car suddenly breaks loose at the rear when you squeeze the throttle (squeeze not snap - think squeezing a gun trigger so as not to disturb the aim - or just: be gentle dude) then drop the bump. I usually work in 0.5 increments until I get it close and then narrow it to 0.2 or 0.1 increments. It typically ends up pretty darned soft. My Nissan R390 is set to around 2.5 at the moment.
Set the rebound: rebound is very NB. Watch the friction telemetry. If the tire loses grip as it rises over a bump (while accelerating or decelerating) reduce the rebound - again, I work in 0.5 increments until I get it close then slow it down to 0.2 or 0.1 increments.
Set the sway (roll) bar: rule of thumb - set the front higher than the rear. Use the friction telemetry window again. Reduce the rear sway to ensure that as you feed in the power the inside tire doesn't lose grip. Try and get the inside tire to maintain grip all the way out the corner. The sway bar is usually set low down on the scale (far left).
Go back and reset the front suspension. You'll need to make minor adjustments after you get the rear working. After that, revisit the rear and ensure that everything is still working and make any minor adjustments.
General: be a smooth driver. Inconsistent driving will always destroy any suspension tuning benefits. Try to get your lap times consistently within a couple tenths of a second of each other.
Using telemetry: I can't watch the telemetry while driving so always tune the car in races. I race - min 5 laps - and then watch the replay with telemetry visible and using the slow motion option.
I started doing this and sucked in the beginning because I didn't see what the car was doing. Watching a replay in slow motion, from behind and above the car (to ensure you're on the right line and to see the car's attitude), with the telemtry displayed divulges a lot of information. I watched a lot of corners in slow motion to begin to understand this.
NB: make only one change at a time. Don't change the bump, rebound and sway bar then test the car again. You won't have any idea what changes made the differences in the handling.
With a decent setup and smooth driving I can get most cars to full throttle at corner exit without any assists (I hate assists and never drive with any - for no reason) and also change gears myself. Changing gears myself gives me absolute control over when the car will shift and experience a change in horsepower and torque applied to the road and thereby upsetting the handling. (As the car shifts it goes off the accelerator and transfers weight to the front suspension then snaps it back on to the rear but at different horsepower and torque values).
Hope that helps. If anyone's got any other suggestions or if I've messed something up - holler!