As I recall, your figure is sculpted in a pretty smooth finish with a few very large indicationsof hair, more like wrinkles on clothing than the look of fur or hair. Dry brushing is not particularly effective on this, nor will a wash have any place to settle.
Okay, that's the problem, let's try to fix it.
For your highlights. lighten your base color and thin it. Apply light coats on the upper portions of the raised surfaces. Now darken your base and thin that. Again, apply light coats to the lower surfaces. Next, mix an intermidiate value of the shadow and highlight and try to blend them to the base with very thin, light coats. You may need several mixes to do this. An airbrush would make the transitions quicker if you use one.
When doing the above, don't use black or white, use tans or yellows.
Unfortunately, while that will give you highlights and shadows, you will still have a comic book art smooth figure.
Some options I can think of...Do you have any flocking material in your workshop...the stuff car guys use on carpeting? That will add texture, though theimpression will be of very short hair (Bigfoot gets a buzzcut!
) Maybe even some static grass? Upiu'll need to apply this before painting.
Your best option may be anthema to most of us...try to get brushstrokes as you paint. Use your cheapest brush and streak darker and lighter versions of your base color in the direction of the hair growth. make the strokes the length you want to suggest for hair, maybe a couple scale inches. Next, take your finest brush and add some very fine highlight and shadow streaks along the hair. Yeah, this is going to take a while.
Good luck and keep us posted.