Replace the wiper blades at least annually for optimum performance.
You can improve poor wiper quality by cleaning the wiper blades and the windshield.   See   Cleaning the Windows and Wiper Blades
Changing the Windshield Wiper Blades
Note:   Do not hold the wiper blade when lifting the wiper arm.
Note:   Make sure that the wiper arm does not spring back against the glass when the wiper blade is not attached.
Wiper Blade Removal
  1. Lift the wiper arm and then press the wiper blade locking buttons together.
  1. Slightly rotate the wiper blade.
  1. Remove the wiper blade.
  1. Install in the reverse order.
Note:   Make sure that the wiper blade locks into place.