Parallel Parking - Pull up next to another car so that the bumpers are kissing. As soon as you start moving back, put one full turn to the left on the steering wheel. when the front of your car reaches 2 Oclock (45 degrees ish), take the turn off and put one turn on to the right. Then, straighten up. this should really help you master the manouvre.
Reversing around a corner - Make sure that you can see the corner of the curb in your left wing mirror all the time. Don't feel that you need to keep excessively close to the curb as you will probably end up clipping it then fail. just take your time, if you rush it, then you are likely to screw up.
Turn in the road - For every movement you make forwards or backwards, put the handbrakre on.
My Test Route didn't involve reverse parking, so i don't really know any techniques! sorry! Can someone else pitch in here?
Just remember that the examiner isn't looking for a perfectly executed manouvre. there is a fairly large margin for error so long as your observational skills are there!