The cross country ski camber refers to the pronounced arch at the center. Since it is held off the surface of the snow, it must be weighted in order to get traction. This type of camber is essential for the performance of the classic kick and glide cross country ski technique. The flex of the ski influences its ability to grip the snow when the skier applies his or her weight to it. If you tend to stay on groomed tracks, because of their gliding efficiency, stiff-flexed skis are your best choice. Most stiff flexed skis have flexible tips, which assist the skier in staying on the pre-made tracks.
Your next point of consideration is one that is often subject to debate: The advantages of waxed vs. non-waxed cross country skis. While non-wax skis might be easier to care for, waxable skis have been known to consistently out perform the non-waxable models.