If you're adding a bi of "extra fluff" make sure you DON'T put it on straight. So, take that little bit of fluff that you want to add, and mush it around with your fingers to make sure none of the fibers are straight. I find this really helps with blending. Then I will also take the tip of my felting needle and try and wrap any loose fibres that haven't felted in yet. Then with all the loose fibers on the tip of the needle, I felt that right into my project. Helps control the fuzzies without cutting them off.
Hope this helps,