Great article, except that it omits the most important, first step: doing the research to make sure you are querying the right production company for your screenplay.

For instance, don't send your zombie horror spec to a company that only does family comedies or Christian dramas.

Another point, make the letter reflect the feeling a producer will (hopefully) get reading your script, particularly if it's a comedy.

And finally, a query letter is an invitation to a producer to engage in a business relationship with the writer. Not a sob story, not a brag sheet. Respect your reader.