If your new to racing 'sims' and have maybe played a little (or even a lot) on racing 'games' then it can be a very different experience to what you might be used to. In a racing 'game' you can maybe get away with hammering up to a bend on full steam before all at once, in the same split second, braking-gearing down from 6th to 1st- whilst simaltaneously turning into the apex - sounds great, and it is, but you can't do this in real life without sliding all over the place and crashing out. Just as you do in GTR Evo if you try it.
If your new to it and struggling, and assuming your controller all working properly (is steering centered and moving sensibly in control settings-advanced - if its not centered it would indicate that the controller is not calibrated in windows and you'll be fighting just to go straight).
My advice would be to go with the simbin car setups, for now, (reduce fuel load and braking pressure) - but dont change too much else, if your always fiddling with settings you think you find an CONTROL SETTING or a CAR SETUP improvement, BUT ITS REALLY YOU IMPROVING. And that will start to happen very quickly if you do lots of laps, try to find a car, any car that you find ok - for me the minis were best for this - and get used to a particular track with a particular car, you'll be surprised how getting it right in one car on one track helps you in all the others - changing cars, tracks, setups, and control settings all the time will just totally confuse and frustrate you, it did me.
In the end I just defaulted set upped everything, got used to default settings and SIMBIN setups as a base line, for a few WEEKS, and then started to build on that.
I could go on and start to quote setup or settings figures - a word of warning on other peoples facts and figures 'What works for one person, on one PC, with one controller, wont always work for another person, on another pc, with another controller or any combination of one or another or even some others'.
So you see thats a lots of possible combinations, setttings, setups, people, pc's and controllers - and we PLAY games for FUN so stop worrying about all the settings, get down to having FUN and it will all start to fall into place...