I am doing a charcoal portrait of my cousin for an art project. I don’t know why, but I can’t seem to get the hang of charcoal. I was wondering whether you might have any tips on how I can produce better results with the medium.
I usually start a charcoal piece one of two ways.
scenario 1: I start by blacking out the page with charcoal and then erase the highlights to form the picture
or scenario 2: I use a more additive approach, adding the ground as I go.

The problem that I am running into is that in scenario 1 my highlights get muddy (the eraser does not get a perfect white), and in scenario 2 the drawing looks too linear and flat… and I loose some of the mid tones that I have when I use the blackout method.
What method you all prefer to use when you work with charcoal, and why?
also, (on a similar note): what is the proper way to use workable fixative. Is it a bad idea to use it on only one part of a drawing? is there a way to get rid of the line where the fixative area stops and the unfixed area begins?