The instructions are broad because the licensing board knows it will be getting a wide range of complaints from people with a wide range of organizational and writing skills. Substance will prevail over form. However, a few tips:
1. First, as to organization, I'd start with an introduction of not over one page in length, summarizing who the parties are, what happened, when and where, and why it is an ethical violation. Next, a section discussing the facts of what happened and why it was a violation in full detail -- maybe two to four pages, double-spaced. Then, close with a concluding paragraph that summarizes what happened, why it was a violation, and requests specific disciplinary action by the board (if you know what action is appropriate).
2. Be sure the complaint is complete as to important details, such as your address, your relation to the alleged violation(s), the identity (real name and trade name, address, license number, etc.) of the alleged offender, when and where it happened, and if possible, citations to specific rules forbidding the alleged conduct and/or specifying how the conduct is punished.
3. Sign it, make sure it is properly addressed, and if the rules require serving copies on anyone, be sure to do so.
4. Send by certified mail, and after it is received, try to follow up with a phone call to see if it was received, is complete, and will be acted upon, etc.
