The fastest way around a given corner would be on the widest radius the road allows, which means entering the corner from the outer edge of the turn, turning into the inner edge (which requires an earlier entry than what you're used to) and drifting back to the outer edge on the exit.
However, the fastest way around the corners is usually NOT fastest way to get to the next turn! You should also take into consideration what you have after the corner you're entering, and if you have a long straight there your line should be altered accordingly. In this case, the most important thing to consider is your exit speed, because maximizing your exit speed will allow you to save a lot of time on the next straight. To get the best exit speed you should brake for slightly longer, enter the corner a bit later, taking a tighter line on the entry and then, as soon as the road allows, start straightening the car and apply more throttle.
For more information you can check out this web page, and the whole site it comes from is also very good.