...when you see an ad in the paper or online, don't rush to apply for it. Stop! Read the job again. Is there a company url anywhere in the ad? Perhaps it's in the reply-to email address: "reply to firstname.lastname@example.org."
Liz suggests that you use the URL to research the company by going to its website or Googling the company name. Then adjust your cover letter and resume to empahisize your qualifications to meet that company's needs and goals.
Excellent advice, Liz. Thank you!