Use a tripod or rest your camera firmly on some other still object. Also, consider a cable shutter release mechanism or using the self timer. You must ensure that the stationery elements in the composition don’t get blurred by having your camera perfectly still.
Since with longer exposure times more light will enter your camera which needs to be compensated to avoid the over exposed shots. For this, choose a smaller aperture and adjust the ISO to a lower number.
Alternately, you can use a neutral filter to cut down the light passing through the camera lens while using a slower shutter speed. Use of hood on the camera will also reduce the effect of stray light.
In the inset picture, the vibrations of the string of the kite have been captured as a blur against the stationery buildings.