This Type of photography is one of the way to express the feeling rather than capturing the moment.
These Pictures were taken in smartphone.

Step 1: Backgrounds for Colored Pictures

If you're going for colored pictures, Find a background which not has much detailing as they're of no use whem blurred.

Step 2: Background for Black & White Pictures

For these, find a beam light Source. For better results, lower the exposure value of your device(camera, phone).

Step 3: Foreground

FOR COLOURED:
Look for objects which are bold in shape and colors & should be big enough to be seen after blurred.

FOR BNW:
The shadow of the object work as the foreground. Hence look for something with artistic shadow even when blurred.

Step 4: Situation

Find a unique arrangement of fore & background so there emerging an piece of art

Step 5: Blur(unfocuse)

After you determine how blurring is needed, focus your device on something near. Distance of your focal point depends on blurring.
In phones this can be done by tapping & than locking focal point somewhere near you.