Scientific papers are for sharing your own original research work with other scientists or for reviewing the research conducted by others.
As such, they are critical to the evolution of modern science, in which the work of one scientist builds upon that of others.
You can similarly prepare your readers for an upcoming division into subsections by introducing a global paragraph between the heading of a section and the heading of its first subsection. Mention these things early in your paragraph, ideally in the first sentence.
This paragraph can contain any information relating to the section as a whole rather than particular subsections, but it should at least announce the subsections, whether explicitly or implicitly. If you use a standard or usual procedure, mention that upfront, too.
Finally, they structure the content in the body in theorem-proof fashion, stating first what readers must remember (for example, as the first sentence of a paragraph) and then presenting evidence to support this statement.
In the Introduction section, state the motivation for the work presented in your paper and prepare readers for the structure of the paper.
To reach their goal, papers must aim to inform, not impress.
They must be highly readable — that is, clear, accurate, and concise.
In a sense, they reveal the beginning and end of the story — briefly — before providing the full story.
Second, they move the more detailed, less important parts of the body to the end of the paper in one or more appendices so that these parts do not stand in the readers' way.