Many of you will find that you can turn sharply in one direction but not the other. This is probably the side that you tend to get on and off your bike on. To avoid having your front tire slide out from under you, shift your weight forward. On steep downhill turns you must compromise between keeping your weight back to maximize rear braking, and keeping your weight forward to keep the front wheel from drifting. On VERY steep downhill turns you may need to turn the front wheel sharply, shift your weight onto it, and ride it around the corner.
Balance is the key to turning very sharply.
Practice balancing with the bike stopped or barely moving. To get over a root or water bar or rock, approach it from a right angle, compress the front of the bike just before hitting it, and pull up with your arms as you reach it. The front wheel will then leap over it. Next shift your weight forward and hop the rear wheel over it by pulling up with your legs. If you are riding uphill, you will need to throw your weight forward as you go over an obstacle.