Web Hacking 101 [pdf]
gironsec.com
gironsec.com
Furthermore, in the later pages the document does mention the OWASP testing guide.
Maybe the title is a bit misleading? Let a mod change it to the original one: "Tactical Web Application Penetration Testing Methodology"
While it's not about technical writing I think Kurt Vonnegut's advice will help you to make a better write up. Specifically #7. -- Pitty the Readers[0]
Vonnegut mentions The Elements of Style[1] which you'll find useful if you're struggling to give detailed explanations
[0] http://peterstekel.com/PDF-HTML/Kurt%20Vonnegut%20advice%20t...
[1] http://faculty.washington.edu/heagerty/Courses/b572/public/S...
http://security.stackexchange.com/questions/21523/sample-vul...
[1] https://www.owasp.org/index.php/Category%3aOWASP_WebGoat_Pro...