Cornering is the greatest quest for the mountain biker as it is almost impossible to master. Phil helps us through one of the hardest variations which is flat turn cornering.
Flat turn cornering involves separating the body from the bike and positioning it almost perpendicular to the ground with weight on the outside foot. This allows maximum traction on the tires and when the tires start to slip, the rider is able to stay upright and slide with the bike without slamming on to the ground.
In most bike rides, there is a wide array of cornering conditions from the flat turns mentioned here to bermed corners to loose dirt or rock filled turns. This is what makes cornering so difficult as the rider needs to read all these conditions and make a decision on what cornering technique to use to get through as fast and safe as possible.
As usual, get the most predictable tires for your conditions and wear knee pads and gloves for these learning endeavors. Flat pedals are handy too to give an extra array of bailout options.
It is a good idea to read all the information possible on a given corner, like soil type, build quality, recent weather, berm solidity and most important, test it out. Never come in to an unknown corner fully committed. Always test and come in a skeptic. Listen and feel the feedback and commit more as the conditions allow.