The language used in the sales letter format should be simple, and suited to your trade. Complicated or complex writing leaves the reader confused and unlikely to read your letter or take action and buy. When a letter writer includes any bonuses, they should be supported with the word "free." For example: "FREE article submission with every SEO article!"
Of course, you will eventually realize that even if you do not get that frenzy over the cover letter format, you will still have to pick one template to start on among many choices. Thus, it pays to know some essential points that will help in making a good cover letter.