Bonnie, shading just takes LOTS of practice but I think you are well on your way. I started burning in 99 and since there weren't any decent instructors around I had to learn through trial and error. It took me a year to figure out a style that would work for me which ended up being what I call the smooth shading technique. Once I figured out a style that would work for me I ended up selling my burner and getting a better one that would do what I needed and it then took me 2 years to really master the shading to the point that I was ready to start doing portraits. After a few portraits I finally had the confidence to continue and now portraits are one of my favorite things to do. They are not easy but if you can capture the essence of the person and not just copy it, you've mastered portraits. You're off to a good start with that one, just keep practicing shading. When I do portraits (human or animal) I always start with the eyes since they will make or break a portrait. If I get those right I keep going, if not, I start over!
Keep up the great work, you seem to be a "natural"
Nedra