1)R is a better button to use for acceleration than the right stick.
2)tap the accelerator during corners.
3)if you cannot play under pressure, lower the brightness of the ghosts(you can do so in options)
4)never ever attempt to beat the record on your first try. always take the first few tries to familiarise yourself with the track.
5)every vehicle handles differently. so at the same time as 4) get used to the car's handling.
6)handling varies greatly when you let go of the accelerator. so if you're turning and the car doesnt seem to be moving, relax the accelerator and turn but quickly press it again and readjust. your RC will turn much sharper than before(depending on car,ofcourse)
7)take your time. since there's no synchronous multiplayer, there's no reason you cant restart the same course over and over again until you get it right.
some courses take me hours just to beat the best time my friends set.