At the World's Greatest Marketing Seminar, a guy named Tom Hopkins spoke about "low-profile selling" - he apparently is one of the masters of selling and has been emulated and idolized for years.
His approach is to focus on the client's needs, to fully explore their needs, and then provide the solution. By focusing on someone's problems or challenges - something they are really well-acquainted with and sick of - you demonstrate empathy, understanding and hope. It's building the relationship around their WIIFM (what's in it for me). Then you can show how they can benefit from working with you.
In job search, a position description outlines the employer's challenges, needs and problems.
An effective cover letter is essentially a proposal to specifically address them.
For example, here's a very short job description that may not initially seem like it describes any problems but clearly does.
Director of Membership
Responsibilities include working closely with the S.V.P. for Development and Membership to direct all aspects of Membership Department with responsibility for generating specific revenue goals; manage staff of 10 full-time and 31 part-time employees; development and implementation of new on-line strategies for acquisition and retention of members; create and administer a multi-million departmental budget; oversee the research, planning and implementation of around 100 events and member programs; serve as publisher, distributor and content manager of Rotunda, the museum members' newsletter; Candidates should have a bachelor's degree and at least eight years of experience with increasing responsibilities and proven supervisory skills. Experience in a Museum environment a plus. Computer proficiency is required—Raiser's Edge experience is a plus.
I've put in bold the needs and challenges contained in this job description. Here are some examples of how to construct a cover letter response to them.
Members are the lifeblood of all museums and, as with all audiences, the challenge is to create an attractive package that both attracts new members and retains existing ones. My experience in building a large, repeat audience for the [organizationA]'s myriad programs gives me the skill and perspective necessary to take the Museum's membership program to its next level of success.
Publishing relevant, timely member materials is key to promoting the Museum's programs and brand image. I understand the importance of the look and content of publications, based on my rich experience preparing and distributing effective printed and digital media while at [organizationA] and [organizationB]. I derived great pleasure from the fact that our most successful materials led members to deepen their relationship with the organization and become financial donors.
The bulk of your cover letter would include such comparative paragraphs and sentences, showcasing how your past experience will help the employer meet their challenges and reach their goals.