Use a wide aperture (low f-stop like f/1.8 to f/4)
Move the subject farther from the background
Move closer to the subject
Use a longer focal length
Use portrait mode on a camera or phone
Increase the distance between subject and background
Focus precisely on the subject
Use a larger sensor camera if available
Add a blurred background in editing software
Use depth-of-field or lens blur effects in post-processing