One of the most relevant aspects of the structure of an essay is signposting: giving clear indications about the content of your writing not just in the introduction, but in every section. Imagine you were giving indications to a driver to prevent them from getting lost: that is the function of signposting language. That way, your text will be much easier to read, much clearer.
This is essential, even at intermediate levels (B1-B2). You can find ideas of signpost language in the document below: