When you establish the grid for each scale to be drawn within, you then can start to slowly work in each little spearhead shape. From there, you always want to shade from the bottom to the top of each little spearhead shape, making sure you leave some negative space around the edges. Leaving some space around the edges of each little spearhead shape will create a distinction between each scale. You also want to make sure that you are shading in scales a little darker if they are on a side that would be less visible to a light source. It will take time, but it will be worth it in the end!