A pretty good rule of thumb for finding a racing line in addition to watching the demo is to pay attention to where the rumble strips are. They are there for a reason, although sometimes it may not give you the fastest time. Also, some cars will get pulled into the wall or off the track if you get up on the rumble strips, for example, the Elise. In that case, try to get as close as possible without actually getting on it.
As for the S-License, the 2 most difficult tests are S2 and S8, although I found S2 way more difficult and the final exam wasn't as tough. Cote D'Azur is one of my favorite tracks and I seem to be able to handle that one well. You might find
this thread useful.
Also check out
this thread. It gives you tips on golding the license tests, so if you try for the gold and are off-pace by a couple seconds, you'll still pass as you only need bronze. It helped me on a the super license tests a few times, but mostly I just kept at it and watched the demo to figure out my segment times. I think most people get really good at the first segment because it is attempted more than the later segments just because you gotta get a "crashless" first segment to even go to the next one. There were a number of times where I'd get good T1, T2, and T3 times, but because I saw the last segment the fewest number of times, I sometimes didn't know what speed and what line to take, often resulting in failure.
Finally, make sure you've mastered the other license tests...on my current game save I did each of the B, A, iB and iA licenses twice before moving on to the S-License. I had to quit my first game save without reaching 100% because I knew I didn't have the necessary skills, having foolishly demolished the lesser races with an overpowered car like an F1.
I beat the S-license Final by using manual and the analog stick as my accelerator b/c with than i can get better control over the car. The new races are awesome as they are loooooooooong and boring too but it doesn't really matter. I also gots the F094/S from the Polyphony Digital Cup 
by using my GT-One Road Car . For the 787B i cheated with my Escudo and using the rubber-band trick lol. 20 laps on that track is immensly boring. I am gonna try the Vitz Race again. Hopefully I will finish that out with a Castrol Supra in my Garage. lol Thank you VERY much for your help. heheh um i just have one more q. How much is that damn 94/S worth. I have 3.2 million $$, but i still can't buy it from my self. Thanks again for all of ur help
