Lower the CG. Different set of tires than stock; preferrably a pinned or knobby tire on a decent set of rims. Soften up the suspension to handle the bumps in stride. Think about sway bars for evening out the chassis roll in turns. Beyond that, the gearing and engine will need to be set up for the style track (short technical, long winding, lots or not lots of jumps, etc.) Each track demands a slightly different set up across the board.