humm loose rocky techniques, im sure jedi would do this better but:
MOST IMPORTANT: stay relaxed on the bike, it should be free to move underneath you, that means no death grip on the bars or clamping the saddle between your legs
if you expect the bike to move, start to lean into corners before you think you need to, that way when the bike takes time to settle in the turn you are still on target
Really important to look through corners where you want to go
Speed really is your friend, you will be amazed at the stuff a modern MTB will go straight over at speed
outside foot down through corners (flat pedals might build confidence)
in terms of tight switch backs ideal is a rolling endo thing as mentioned but you can get round 99% by slowing right down, drop the outside foot, swing out wide, turn in tight, use the rear brake to help the back round if required, look up and pedal out
bike setup ideas include: wide bars, heavier wheels/tyres/tubes
hope that gives some help and ideas