Often times the users of HackerTarget.com are not experts in the realm of vulnerability assessments. In fact many are not sure where to start and are confronted with a bunch of free tools available online for immediate use. The tools have a variety of different uses leaving beginners unsure of where to begin.
I have put together a quick flow of the general process that one would follow to assess a domain name. This will you to discover various systems associated with the domain name, and assuming you have permission each of those can be assessed for security issues by following this flow.
If you are interested in a more comprehensive security vulnerability assessment methodology we highly recommended the recently released version 3 of the OSTMM – Open Source Security Testing Methodology Manual.