The technique of using small apertures is used to adjust the amount of light that comes through the camera’s aperture by changing the size of the hole that the light comes through. Decreasing your ISO is another technique “to compensate for the extra light that a longer shutter speed lets into your camera.” This is done by adjusting the ISO setting which affects the sensitivity of your cameras image sensor. A low number will allow you to choose longer shutter speeds being less sensitive to light and a high number will make the image sensor more sensitive. Another technique to control the amount of light when using a longer shutter speed is try using a filter, specifically the neutral density filter. This type of filter is “helpful in slowing the shutter speed down enough to still get a well balanced shot.” This technique is useful for shots of motion blur taken in the daylight. Another filter, a polarizing filter, also cuts some light out. There are other techniques that can be useful, such as slow sync flash which “combines longer shutter speeds with the use of a flash so that elements in the shot are frozen still while other are blurry.” You can also move your camera along with a subject that is moving to capture an image where the background is blurred and the subject is in focus, which is known as the panning technique.
Rowse, Darren. How to Capture Motion Blue in Photography. Digital Photography School. https://digital-photography-school.com/how-to-capture-motion-blur-in-photography/
Good, thorough summary.