Typically, you will want to use 2-3 heading levels.
You need to clearly differentiate these in style, so that it’s easy for readers to see what you’re doing. use a bold 15 point font for main headings, a bold 13 point font for subheadings, and an italics 12 point font sub-sub-headings.
Each strategy is highly recommended by its proponents as the most effective, but the fact is that scholarly authors differ and even the same writer might vary his or her strategy depending on the circumstances.
A Ph D candidate writing a first research article may find a journal’s instructions for authors incredibly helpful for organising and drafting the paper, but if the object is to transform a thesis chapter into a publishable article, the goal will be reshaping that material to fit the new context.
Remember that an excellent presentation that conforms in every way to the journal’s requirements may not render poor research publishable, but a poor presentation can certainly doom excellent research to rejection.
Most journals provide everything you need to know to prevent this, so use it well. Learn about the aims and scope of the journal you are considering and keep them in mind while you plan, write and edit your article.
Also, even though it’s an essay, sub-headings can be immensely useful.
Check your subheadings – if, without any further information, they tell a logical story, you’ve probably worked out a useful structure. Again, there is a lot of flexibility for how exactly those are prepared, and it depends a lot on which journal you’re writing for.
Some journals will outline virtually everything about an article’s length, structure and formatting, and a good deal as well about its content.
Pay special attention to information about sections, headings and subheadings and to the relative placement of these elements.