One of the greatest fears for new drivers, perhaps even more than drunken motorists or three-lane roundabouts, is the possibility that one day they will have to parallel park. Admittedly some drivers go through their entire life avoiding parallel parking, but these people are an exception to the rule and often spend a lot of time walking to and from their cars anyway.
It's really pretty easy:
Find a suitable space; be realistic about whether your car will fit into the gap - there is nothing more embarrassing that attempting to park only to find that your car is too long or the space is too short and you have to drive away a failure.
Stop in front of the space. Reverse slowly, and about when your seat is in line with the back wheel of the car in front, turn into the park so you are facing 2 o'clock or 10 o'clock depending on which side of the road you drive on. Keep reversing until your kerb side front bumper reaches the rear bumper of the car in front. Then turn the steering wheel straight and pull in level.
Some minor correction may be required, but no more than one or two turns; remember if you need 38 turns to get in, then you'll need 38 turns to get out.
Here are some further tips:
Use the reflection of shop windows to see how much space you have between the cars in front and behind.
Get a tow bar. If you do misjudge the distance behind you, at least you won't care.
Buy a car like Herbie the Love Bug1 which can drive sideways.