Check out any fantasy story, whether it be a multi-volume epic or a three-page short, somewhere in its prose is the use of magic. What makes or breaks the fantasy from that angle is the logic of the magic.
Now that may seem to be an illogical turn of phrase in and of itself, but in order to work in a story, magic, if used must be logical. Human beings, even the writers of fantasy are at their core logical. Not in the Mister Spock sense, but more in the Doctor McCoy sense. We don’t mind a little illogic as long as it makes sense.
In order to fill that need, the system of magic you build must have its own laws. Certain actions must have results that make sense. The use of power has to have some sort of consequence, and sometimes, the greater the consequence the better the story.
One very good way to develop this is to consider your magic user, be they a being of power, wizard, sorcerer or witch, to be a type of athlete. As with any sport or athletic contest some will be better or stronger than another. In many sports it is not the power but the skill that prevails, and the skill is based on practice.
Consider that when you next write.