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!"
Your cover letter format is very important to your success. With a high quality motivation letter, your chances at getting an interview will dramatically increase. Don't take shortcuts. Pay attention to both what you say (content) and how you say it (format). Your efforts will pay off in your career success!