you need to make it easy enough to drive on the limit, for your driving style / ability, for however many laps the race is. For someone in need of asking this question
this would probably involve a softening of the rear anti roll bar, to reduce the oversteer.
You then need to adjust the tyre pressure and camber for the best compromise of grip. You probably want the inside of the tyres to heat up to about 10 degrees above 'optimum' for the tyre you've selected, and the outside to get around optimum. This will vary, there will often be a 'cold' side of the car that won't get up to temperature, with a bigger variation between inside and outside temp.
Then adjust brakes if need be to reduce lockups.