The power steering is an aid system that helps reduce the force needed to turn a steering wheel. You don't want to drive a car with power steering issues.
How to identify power steering faults.

Whining sound: If you hear a whining noise while turning your steering, the power steering pump is failing and needs to be replaced.
Stiff steering: the steering gets stiff when the power steering pump fails.
Squealing noise when you start the car.
Steering wheel slow to respond.
Never allow the pump go bad due to lack of oil, this can spoil the steering rack too.
Before changing the pump check if there is any leakage ( check the condition of the serpentine belt, if it has spoilt due to contact with power steering fluid). Also check the level of the fluid. If low fill to guage and check again.
Steps to changing power steering pump.

Remove the hose taking fluid out of the pump.
Remove the sensor plug.
Unscrew the securing bolts.
Remove the serpentine belt.
Put power steering oil into the new pump.
Roll the roller on the new pump until it start vomiting the oil.
Close the outlet hole.
Install the new pump.
Fix the sensor conector.
Fix back the hose into the outlet hole.
Fill with power steering oil.
Use your hand and close the pump while someone else turns the steering. This is a bleeding process.
Gauge the pump.
On the car and turn the steer from end to end.
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