Underline and italicize to help make it even more visually distinctive. Busy attorneys and SIU managers want to know exactly what the results are, and they don't want to have to wade through the report to do so. Only make recommendations, if they are warranted. Your recommendations should be limited to the need for further investigation and what that might entail unless otherwise asked to do so by your client. It is tempting for many of us to interpret what is going on, but our job is only to report the actions or activities that we see.
Interpretation is up to the client.
Head each page with enough information that if the report pages get separated, the client knows where it belongs. You might put the subject's name there instead of a file number. Always, Always, Always check your report for spelling and grammar errors. If you don't have grammar and spellcheck on your computer, have someone in your office edit your reports for you. Whenever you have documentation relating to a specific part of your report, refer to that documentation within the report.