How do you avoid brush strokes with pens or markers?

I recently just bought Faber Castel PITT artist pens and decided to experiment with them.. but, are there any strokes or different techniques that would avoid the visible brush strokes shown when overlapping while coloring or shading? (aside from one shot) Because I was shading in the hair, and brush strokes looked obvious, and caused the area to become darker than I want it to. Any tips please? Thanks. (: