Whenever you design something, it is important to include equality and quantity to the design if you want it to look right. Imagine designing a building; you must proportion the design correctly and be sure that the symmetry is correct or the building may appear lop-sided, out of shape, or could potentially tear down over a period of time. The same applies to art.
        
             
        
        
        
I only know two and they are 
1. Not discussing issues and not supporting them with information.
2. Not giving advice on what to say/talk about.