If you don't feel secure with the proces of tampering with setups, I can recommend that you stick with the default setups. While they are certainly far from perfect, they are pretty good when you are learning the layout of the tracks, and getting a feel for the competition. I really like quickraces set to 10% length, with the default setups. They have a fair amounts of understeer, so spinning out shouldn't be that much of a problem. But beware, there are still lots of things that can send you spiralling off the track.
You need to get a good feel for when you can floor it, and when you can't. Throttle control is very important and so is brake control. Generally, I floor it once I pass 120 kph, but sometimes you can do it immediately at much lower speeds and at other times you just can't. Flooring it right after the the chicane at Suzuka will send you spinning every time, while flooring it right after the chicanes at Hockenheim probably won't. Learn to brake all the way to the apex of the corner and then gradually apply more and more throttle. That way you won't make the most common mistake (powered oversteer), which is to floor the throttle too early and too hard (somewhere between turn in and apex) because you braked too much. You will only make one of your rears spin up too fast and lose grip, and hence control.
Practicing smooth and flowing doughnuts is a great way to learn throttle control, since you constantly have to change the level of throttle applied and the steering angle to keep it going. The more even the flow, the better the throttle control. And as an advanced lesson, you can try to set the wheel straight after you induced the spin, and only keep the doughnut going with your right foot. That should tell you, that it is actually possible, not only to avoid spins with good throttle control, but also to make small adjustments throughout the entire duration of the corner, just by making minute adjustments to the level of throttle.
Curbs is another hazard. You can send car spiraling down the track at over 300 kph if you hit the wrong curbs. Learn which to use, and which to stay well clear of.
In any case, its very important to know the track by heart and not only the curbs. Some corners are constant speed corners, while others demand that you keep slowing down right until you exit, and some can be powered through right from the turn in. Identify what characteristics each corner has, and remember fixed points that mark when you do what. It goes something like this: "there is the Fedex ad, so I floor the brake and gradually release it while I downshift, and by the beginning of the curb I turn in at the top of 1st gear and slow until I have one green led lit (which is easier to check than somewhere in the range of 100 kph). I keep this speed until I clip the inside of the corner, and then gradually start to apply more throttle. When I get to the middle of the track, just before the shadow cast by the big tree, I reduce steering and I have a little throttle left. As I exit the shadow its safe to can floor it, and I reach the top of 2nd gear, shift to 3rd and steer straight." Practicing this can seem artificial, and of course you don't actually say all these things in your head. You just keep exploring the corner until you get it right, and then remember what to do when. The replay function is a good tool to use here. Before you know it, it will feel totally natural to do this at every corner on every track.
I hope this helps and sends you in the right direction. Practice is important, which cannot be stressed enough, but remember the most important thing is to have fun. If you find it too frustrating and can't get to terms with your setup, then forget the setup, engage Traction control, and blast through a few races. You can always come back and try again without it.
It's only after we've lost everything, that we are free to do anything.