I wrote a style guide for STEM posts that you might find interesting (or not, up to you): Procrastilearner's Style Guide For Science and Technology Posts.

That one Shutterstock image might not be free-for-reuse? Even though it is on Pixabay it is a sponsored ad image so I think it might not be a free for all. I could be wrong though.

Be careful or the Steemstem curators might downvote you for that (just a friendly heads up).