For what it is worth, I have driven RR cars my entire life and Auto-X and Ice-X classic RR Beetles and classic RR Porches. I drive an old RR Porsche as my "winter beater" specifically because I like the handling characteristics in icy and snowy conditions. So I know a fair amount about counter-steering (IRL I can honestly say that I'm extremely good at it. I'm not as good at it in virtual racing because IRL I drive so much based on the G-forces I feel in my body, not just my wheel.) For virtual racing I use the DFP, G25 and Fanatec GT3RS V2.
Anyway, my advice:
1) Grip the wheel firmly but don't death-grip it. This will help tremendously.
2) Learn to use the "centering" of the wheel allow it to spin back just the right amount and then stop it there. This means you need to know your car very very well so that you know exactly when to stop the wheel's progress. (I've read some books that tell you not to do this, but IMHO it works very well.)
3) This goes back to knowing your car well: Learn to do this in just a few cars. It will help if they are similar in balance (for example, all MR cars or all RR cars).
4) Tune the driver, not the car. Assuming you are starting with a reasonably decent sports car in the first place, you won't need to tune the suspension. Learn to drive the car first, then when you know you are getting 99% out of it you can start fiddling with the suspension settings. Otherwise you're likely to make it worse.
5) Counter-steer smoothly and don't be afraid to spin the car repeatedly while learning. If you screw up and let the back get very loose then don't be afraid to counter-steer a LOT to catch it (I'll stick a video link at the bottom of me counter-steering in an event where I very nearly spun my beetle. But because I know the car so well, I was never even really worried about it. It did totally hose my time that lap though).
6) Fight the wheel. This is true in both real racing and virtual racing with a FFB wheel. You have to control the wheel. You want the wheel to do exactly what you want, no matter how many forces it is applying to you. Sometimes this is letting the wheel do what it wants (such as when allowing it to spin back towards center), but even then it has to be YOUR decision. The wheel is only doing what it wants because that happens to coincide with what you want. Get it? Keep the wheel in control at all times. It can be tiring even in virtual racing.
Hope that helps.
Video link of nearly spinning a beetle followed by doing the same turn properly (
note: Your steering inputs should be smoother than observed in this video. These older Beetles didn't have responsive steering and in order the get the car around an autocross course quickly I have to really manhandle her.)
http://thatmacguy.com/autocross/oops.mov