When building a bicycle wheel there is nothing more important than even spoke tension. A finished wheel with even tension substantially increases longevity and decreases maintenance in a wheel’s life, as opposed to a wheel that is true with substantial tension variance. — The Wheel Department
Park Tool provides a way of visualizing spoke tension, and tools.
You learn to visualize this in your head.
But the Park approach provides a good start for learning how spoke tension can indicate underlying rim damage.