Know your car and how to control it. Smooth and balanced. In order to do this, do it in good time. The less an examiner notices about your use of the controls the better it is.
In terms of steering you may cross your hands so long as this does not result in a loss of control. It is better not to cross when you are driving. If nothing else, not crossing will slow you down when turning corners. This in turn will give you time for a proper look into the road.
With the gears it is quite acceptable to miss a gear out. This is called block changing. There is no longer any need for sequential changing. Every time your hand leaves the wheel and the clutch goes down you are less in control. Match your gear to your speed.
When braking ease off at the end so as to remove the jerk when you come to a stop. Use your handbrake properly. Make sure it is fully released when you move off. If the red warning light is on because you have not released it properly what other danger signs might you miss.
You must know and be able to operate all the controls in order to keep the car safe. Having an understanding of what the various lights and dials mean will also keep you safe.