There is little dispute about the value of a well written and focused resume cover letter. Sending out resumes has only one purpose; to generate interviews. A well written resume cover letter is written to introduce the resume and motivate the reader to look closely at the resume.The sad fact is that many job hunters still slow up their job hunting progress by using letters that directly hurt their job search. They think a one size fits all or a “form” letter will get the job done. Hardly; it’s only a recipe for the resume to be discarded and not read.Here are three mistakes to avoid in using and writing your resume cover letter.1. Failure to understand the needs and purposes the recipients will be looking for in the cover letter. Your resume and cover letter will be sent to three distinct individuals.First is the hiring manager; the person who can make a decision on hiring. Second is the Human Resource office; their job is to screen out candidates who fail to meet the qualifications of the job. And third are third-party recruiters; are looking for specific skills to help sell your candidacy to an employer.To be a strong candidate for the hiring manager they are looking for someone who can have an immediate positive impact. Focused accomplishments go a long way to sell this individual.The HR screener is looking for a close match to the listed qualifications. Your letter should then be crafted to address this requirement.The recruiter is searching for candidates who will wow the client. If the client is looking for an operations manger with three years experience and you have six years, with program management experience it becomes a rather easy sell.Knowing your audience for your cover letter will allow you to craft the letter to meet the needs of the reader.2. Failure to introduce your resume but repeating the same things you wrote in the resume. You worked hard on your resume and are proud of the effort. Repeating what is in the resume will announce to the reader that you are wasting their time if they begin reading the same thing twice. Maybe you think the creative well is dry; you have nothing further to add. Well think again, because the letter to be effective must be creative.The first sentence must grab the reader and motivate them to read further. After the first paragraph they want to read the second paragraph, and so forth. The cover letter is a document meant to sell; and sell you effectively.You are in business to sell your skills and provide benefits to the employer. Make sure that every word and every sentence speaks about the value you are about to bring to the company.3. Failure to focus the cover letter to the proper story line. Every time you talk about yourself in the cover letter that means less space in the one page letter to selling what you can do for the employer.Edit out the “I” and “Me” from the cover letter as much as possible. Do the research and focus on how you can make a difference for the prospective employer. The employer doesn’t care about advancing your career but the bottom line and your enthusiastic commitment and interest in the job. The story line is about the employer and not about you.Carry this off and eliminate the other mistakes and you’ve got a winning cover letter.