Skewing is a very common issue for artists. When we draw faces or people, one eye might be too high or maybe we unintentionally draw every character leaning to the right. These little inaccuracies may be a result of the angle of our drawing surface, paper angle, our head tilt, wrist movement or some combination of these factors and others. During the drawing process, our mind grows accustomed to a slightly odd angle here or there, and we may be oblivious to the fact that the drawing leans one way or the other. Often, facial proportions are asymmetrical.
There are some simple methods to correct this habit. When working digitally, flip your image horizontally from time to time to help yourself observe the shapes from a fresh perspective and fix them. When working traditionally, occasionally view your work reflected in a mirror or hold it (with the image facing away from you) in front of a light source so that you can see the reversed image.
Another technique is to draw a line or plane fr