Step 4: Hints and tips
Practice first on an empty street, just reversing until you are parallel to the curb and the correct distance away.
Try practicing between dummy cars; my father stood wooden pallets on edge to represent the ends of parked cars. When I clipped them, they went down with an almighty bang, but did no damage to my car. If you cannot get pallets, try stacks of boxes with noisy object balanced on top.
Memorise where the curb is. Many car rear screens have manufacturers' stickers on them - does the curb line up with one of them when you are parked properly? If not, add a tiny piece of clear stickytape to your window as a marker (if your driving examiner asks why it's there, tell them it's where you took the for-sale sign off when you bought the car).