As for driving style... the most impact on laptime is the speed with which you come out of a corner. Many people seem to think that braking late for a corner will gain them more time, but it actually doesn't.
If you think about this, it makes sense... if you come quicker out of a corner, you'll reach higher speeds all over the straight and thus gaining seconds, while braking for a corner is only over a very small distance of the track. I discovered with previous racing simulator experience that I was braking way to late and that I actually improved my laptimes by braking earlier and steering into corners more smoothly, both my corner speed and exiting corner speed improved a lot which in turn helped me to shave off seconds from my laptimes.