Toning is very important in portraits ( also some other stuff but it doesn't matter). Giving a face the proper tone is essential if you want to make it look real and not details , as some of you may think. The process of toning should not be rushed , use pencils that progressively range from HB to 8B. Slowly smudge the surface before going for another pencil. By the way, his left eye isn't important, it's going to be black anyway.