On today's busy roads reverse parallel parking, as with all reversing manoeuvres, is a potentially dangerous manoeuvre and should always be executed with care.
On your driving test, if asked to perform a reverse parallel parking manoeuvre the examiner will expect you to:
1) Reverse into a space of about two car lengths,
2) Park your car at the Curb safely, smoothly and under control.
3) Perform effective all round observation
4) Remain at a safe distance from the parked car,
5) Do not mount the Curb and stop reasonably close to it.
Different driving schools teach different methods of how to reverse parallel park. Here is one of the most popular.
1) Make sure that the parking space you intend to park into is at least 2 meters longer than your car.
2) Pull up beside the vehicle in front of the parking space. Try and keep as little lateral distance between the two vehicles as possible.
3) Check your mirrors before you stop in case you need to indicate your intention to stop to a following road user.
4) Stop and apply your hand brake. Change straight to reverse gear. Check your mirrors and do an all round observation including checking your blind spots. If all is clear look over your right shoulder and begin to reverse.
5) As the back of your car passes the back of the front car quickly steer left full lock.
6) When your car turns to an angle of 45 degrees turn the steering wheel right full lock.
7) Using your left wing mirror as a guide wait until the car is parallel before performing the last turn to the left to straighten the wheels.
8) If needed move forward in order to straighten up your wheels.
9) Apply the handbrake and select neutral or park.
For more help try this parallel parking video tutorial. For extra help on mastering the driving test manouevres this driving test dvd may prove useful.