Not sure what your experience/background levels are but I found this a minute ago from google search, so haven;t used it myself, but imagine its roughly accurate
TBH mainly comes down to experience on the circuit and time in the game, getting used to physics.
I haven't played car games, or any pretty much any games for 10 years until past year and I'm a B driving online and whizzed through most the Americas CE' so far, only the Weathertech Laguna Seca is causing me issues. I started to take on the Green Hell, and golded first 3 or 4 sectors, but have barely played the past month or so due to holidays, school holidays and work commitments...