We usually use 2B-8B. It's dark. You can use 8B. If you think clearly, it depends on your painting level and experience. Practice arranging cables more. Don't underestimate the flat cable. You can buy some beginner's circuit books after practicing the cable arrangement. What you said is very black and clear. Is it a combination picture of fruit bowls and jars in life? Hehe, if you want to be realistic, draw more pictures and find out the problems. Correct in time and sum up experience. Mainly pay attention to the arrangement of lines, straightforward. Don't hesitate to look at the lines drawn, which are evenly arranged layer by layer. It looks very clear, don't draw back and forth, remember.
If you draw a human head, 2B-8B can also solve this problem. You can draw a good picture, which is used by our teacher. Paint your hair as black as 6B-8B. You mean the pencil sharpener? Not the main reason. You can draw in the center, and it's dark. The center is drawn with a pen tip perpendicular to the paper. If it is less than 90 degrees, it can be called flank. )
I can only tell you this. I hope you will make greater progress.