Practice!
Well, I'm currently working on getting the S License so I can be of some help.
This may seem pretty obvious but, stay to the inside, this makes you run a smaller circumference. you're going to have to repeatedly lay off the gas as you feel/hear your car sliding away from the right edge. And I mean as soon as you feel it creeping away ease off and realign or you'll lose key seconds. Also, don't be afraid to roll on the red and white tracking on the edge. Additionally try to stay in 3rd gear and bust out the speed in a straight line at the end aiming for the wall afer the finish line. (just make sure it's the third lap.)