These are edges which touch each other, but do not overlap. They can cause unnecessary visual tension and confuse the eyes. Similarly, even if the objects don't touch, but are simply too close to each other, it can draw unwanted attention. The fix is simply to either overlap the two objects, or separate them further.
Avoid tangential lines
Lines from separate objects that run into each other to form a single edge can be confusing to the eyes. You can fix this problem by shifting the objects to break the alignment.
Avoid scattering objects to the edges
Arrange your objects toward the middle of the painting. You generally want the focus of a painting to be on the interior, and objects scattered around the outside will distract from that.
Avoid lumping all of the objects together
While you want the focus to be on the interior of a painting, crowding everything too tightly into the middle of the painting creates a dull or overly tight painting . Break the masses apart by distributing one part a little way away from the center of interest for a better balance.
Avoid stacking objects on top of each other
Be careful not to put things directly in a row, either vertically or horizontally.
Avoid drawing objects that point out of the picture
Items that taper to a point and are close to an edge have the effect of leading the viewers eye out of the painting. The solution? Turn them around so they point toward the center of the design.
Avoid parts that come together at a single point
It is an exception only when you intend it to be the focal point as you design a drawing. You can break up the star or downplay some of the elements.
Watch out for objects that run off the painting
Things like rivers and winding roads can act like “trails” that lead the eyes out of a painting. You can stop the outward flow with a vertical shape like a tree or a rock. That way you can redirect the eyes and keep them inside the picture.
As you become better at catching these common pitfalls when you design a drawing or a painting, it can be so much fun to dive into your creativity without being hampered by them.