Having a good scientific idea and writing a good paper out of it are the most important steps in order to publish in high-ranking journals, but they are not the only steps needed. The other steps are writing a good cover letter (to convince the editor) and good answers to referee reports, if needed (and this is almost always the case, based on my personal and and colleague's experience). Cover letters and rebuttals are a sort of "grey literature", in the sense that are carefully written, but not published, but only read by a few people (editors and referees). 

Therefore one can learn to write good papers by reading good papers, but one cannot learn writing good letters and rebuttals by *reading* them, since they are not published. 

In the light of this, how one can *learn* to write successfull cover letters and rebuttals?