One of the most common mistakes made during this heat styling step is the direction we guide the flow of air coming out of the blow dryer.
The cuticle layers of the hair are comparable to that of scales on a fish. If you have some experience cleaning fish, you know that the best way to raise those scales are to use the knife against the way they lay.
The cuticle layers of the hair are pointing toward the end of the hair strand. Blasting air in the opposite direction lifts the hair cuticles and making it more prone to damage, tangles and roughness.
Guide the air flow in the direction the hair grows for shiny hair and flat cuticles.