There are a lot of resources out there about writing good cover letters, but they all come down to the same basic tips.  To make sure your cover letter is really great:

Write a new cover letter for EVERY job you submit your resume for. A generic cover letter looks like you just don’t care enough to research the job or the company.  Your cover letter should really explain how YOU fit into their corporate picture.

Tell them what you can do FOR them, not what you want FROM them. This means you need to really sell yourself as the best candidate by thinking about what THEY need, and then explaining how you can provide that.  If they are looking for someone who can design brochures, make sure you highlight the fact that one of your recent brochures led to the highest sales in the past three years for your current employer.  Of course, you’ll need the facts to back you up.  Never make a claim you can’t support!

Show them that you care about what they do. If you are truly interested in working for a particular company, you need to spend some time researching what they are all about.  Include a fact from your research in your cover letter.  Include industry stats, sales figures published by the company, or use part of their mission.  This type of information is widely available online.

Sell yourself as the ideal candidate. Have the job listing at hand as you are writing the cover letter, and make sure to mention how you meet their key job requirements.  Don’t restate everything that is on your resume, but give them enough to keep them reading!

If you have a connection to the company, mention it. Did Joe Howard in Marketing mention the position to you?  Do you routinely use the products they make in your own home?  Any connection you have can show the hiring manager that you “fit” into their culture.

Keep it short and polite. The hiring manager likely has a limited amount of time to spend on your letter and resume.  Focus on the job requirements and highlight a few of your key skills.  And be sure to thank him for his time!

Keep the tone positive and professional. The cover letter is not the place to explain why you are unhappy at your current job, nor is it the time to reveal personal information (like your marital status, religious affiliation, or political allegiances).  Stay focused on their needs and how you meet them.

Include a call to action. Tell them how to best reach you, or explain when and how you will be in touch with them.  Explain that you wish to discuss your qualifications in person.