knees to have a good rotation over the bar.
By default front knee would be in bent position from the starting.
Make sure to maintain that posture. However the take-off leg should be brought to a bent position along with the lead leg during the process.
Hands should be kept tight with respect to body but you can wrap around towards your feet also. This will serve you dual benefit; it will prevent you from touching bar and will speed up your rotation.
To increase the speed, always try to keep your arms and legs as close as possible to the centre of gravity. This is the only possible way in which a jumper can increase his speed of rotation after take-off.