I'm not an amazing teacher but the tips I'd give is, sketch out ever so lightly what you want to draw, so all the important outlines and then start mapping out details you'd want to add so you know where you want them. Then with the shading start with the lightest and boldest parts first, so for mine I'd do the pupil and then all the areas I want to add shade. Then start building layer by layer, slowly getting darker so that there's no harsh changes in shade and it'll look more natural.