#4: Use Selective Focus

"Another ways to simplify and soften backgrounds is by
restricting sharp focus to your main subject.
Using a moderate telephoto lens or zoom
setting with a wide aperture enables you to
restrict the range of sharp focus to just a few feet.
Shallow depth of field is a particularly
effective tool for shooting individual portraits.
By tossing the background totally out of focus
your attention goes directly to the
person in your photograph."

Jeff Wignall
The Joy of Digital Photography
pg. 108