Scrying is a skill, like any other, and takes practice.
Do you know how to open a spirit seal? The same gaze that is used to do that, is used to scry.
Open the seal of a spirit that teaches clairvoyance, such as the archangel Gabriel, or the spirit Sastan, with the intention of learning to scry, and once the seal is open, transfer your gaze from the seal to your dark surface (if using water, it should be in a dark bowl so that when you gaze you don’t see any light reflected).
Here is an inner scrying technique that can help you develop the ability:
If you are really interested in learning to scry, I recommend EA’s Mastering Divination course, which covers scrying into water, blood and fire in depth.