1. If you are making a report, for bureaucratic purposes, the Executive Summary should give away the crucial points in the first paragraph. Background, etc., can wait--unless you have discovered something so crucial it belongs in that first paragraph. In any case, a long report can have a longer executive summary, but again the first paragraph or two should give it all away.
2. The report should be organized so that a busy reader can figure out what is going on by the headings and subheads, and each section should begin with a paragraph that gives it all away.
3. Visual materials are now necessary in almost all reports, since they are so readily put together, even videos for electronic documents. But they should, again, be self-evident, although you can say something in the caption. Pretty pictures, or scandalous ones, are nice. But what you must do is be sure that those images work for your theme. Charts should not be so complicated (or if they are, relegated to an appendix) that their main point cannot be discerned immediately. Same for tables of figures. Highlight what matters. Give a sense of the reliability of the figures.
None of this is news. But it matters to the busy reader. The eagle-eyed lawyer who represents someone out to counter you, needs to be satisfied. But that can be dealt with in notes and appendices. Make sure the main innovative ideas are obvious from line 1 or 2.
I think about this every semester when I read final papers. By the way, this is even good advice for scholarly papers, although the disciplinary norms are also very important. And make sure the title of the scholarly paper gives away your main point. Cute is popular, but informative works better. Akerlof's "The Market for Lemons: Quality Uncertainty and the Market Mechanism" gives it all away once you discover it is about used cars and asymmetric information. (Nobel prize too.) The title is cute, but since it is essentially the takeaway, that is ok. Most of us do not have so useful a citrus fruit in our lives.