You're creating a sketch of some animals at the zoo, using a pencil. as you draw, what element of visual art do you need to worry about less than the others?

When drawing a place surrounded by animals, humans, buildings. you would want everything to be proportional and by doing that you'd practice in perspective drawing making sure everything looks as realistically correct as possible.

I think the color because when you are drawing a sketch it's sketching not coloring

Dynamic symmetry should be the answer

All of the above have been used in film noir.