Technical writing is usually fact-centered, formal and impersonal. However, the key to writing good professional reports is to focus on the final readers. Know your audience and you can then decide your contents and style accordingly. A classic example is Da Vinci, probably the first writer of user manuals for his inventions. As a freelance he had no choice but to send motivational letters to get gigs. Da Vinci does not recite past achievements and employments. No, he focuses on the needs of each client he asks for work.
Other typical suggestions for improving common report deficiencies are using better thematic organization, avoiding inappropriate narrative, and choosing the right theme subjects to enhance textual coherence.
Finally, you should always end on good terms and as amicably as the topic permits. Some controversy is healthy and gives you visibility, but, in the end, honey catches more flies than vinegar.