This is a quick and easy way for a person to put a pillowcase on a pillow without assistance.
Steps

Step 1. Grasp the closed end opposite the open side of the pillowcase
Take the seam in the middle with your hand.

Step 2. Without letting go, put the pillowcase on your hand
Now she's turned inside out.

Step 3. Take the end of the pillow with the same hand that holds the seam of the pillowcase
The pillowcase seam and pillow seam should now be in one hand.

Step 4. Pull the pillowcase over the pillow
Pull all the way, straighten the seams and you're done.