While dry brushing is still a valuable technique (and raised to an art form by Francois Verlinden) it has really been surpased by pre and post shading with an Air Brush, and Filter/wash applications.
The reason for this is that drybrushing lightens raised surfaces, not very realistic, when its flat panels and horizontal surfaces that would be bleach more by the elements, and thus be lighter.
With all that said, it is totally upto you how you build your own kits, there is no right and wrong way.