The shutter speed you should use depends on the lighting in the scene. It is also based on your preference on the results you wish to achieve.
This is a rough guide that I came up with for my own use. I’m sharing the list to help fellow budding photographers. You may want to experiment and come up with your own list of preferred shutter speeds.
1/1000 second or faster
At this shutter speed, you will be able to capture frame-filling action shots. The actual speed to be used depends on the speed of the action, the distance from the action and the focal length used.
When you are zoomed in using a telephoto focal length, a small movement will translate into a greater movement in the viewfinder when zoomed in as compared to when you shoot at wider focal lengths. Likewise when you shoot at a distance nearer to the subject.
This shutter speed allows you to achieve action stopping effect and it works well in most situations. However, certain movement might still be too quick to be captured at this speed and, as you have guessed, you will have to increase the shutter speed.
When the action is moving towards you, you can freeze the action with this shutter speed. Of course, you can use faster speeds to freeze the action but 1/250 second is fast enough in most scenarios.
This shutter speed is good for capturing rain. Water droplets will be captured as streaks at this shutter speed. Faster speeds will render the droplets as shorter lines while slower speeds will generate longer streak lines. The shutter speed of 1/60 second gives a result that I prefer. Experiment and see what speeds give you the desired result.
1/30, 1/15, 1/8, 1/4 second
These speeds are slow enough to create blurring of the scene when you pan the camera. You press the shutter and move the camera while keeping the subject at the same spot in the viewfinder. This will render a photo with the subject in focus while the background is blurred.
It is important that you take note of the background! The background should have different colours or different shades of the same colour so that it will generate blurred lines. If the background is of uniform colour, you will not get the streaks of lines characteristic of the panning effect.
1/2 or 1 second
If you want to create the silky effect when you shoot moving water, these are good shutter speeds to try. An exposure of 1 second gives a softer feel to the water flow.
Above 1 second
Exposures longer than a second are usually used for low light and night shots.