Use for riding on rough ground, it will give you that double suspension effect.  Also best for going up hills and down, on easy sweeping corners, and jumping.

 

The best way to tackle standing up is to stand crouched with your knees slightly bent to absorb and bumps, grip the seat with your knees to help you remain stable.  Keep your elbows up with your head above the bars.

Use this for cornering and great starts

 

You need to sit as far forward as possible to get the weight shifted towards the front of the bike by  crouching & leaning forward.  Keep your elbows up so that your arms are in line with forks.  Gripping the seat/tank with legs will help you feel more secure.  Keep two fingers on hand controls so your ready to make quick adjustments.  Most important is to look ahead all the time.

 

If the back starts loosing grip shift your weight back towards the middle of the seat. This will add weight to the back tyre giving you more traction and help you gain control of the bike again.  Make sure you keep your head above the bars though to keep some traction on the front end.

By standing up your ride will feel a lot smoother as you are effectively doubling your suspension.  This is aid you greatly as you will not get tired as quickly as you would have done in the seated position.

Staying in a centralised position on the bike will take strain off you and keep the wear even on your front and rear tyres.