Just thought I'd pop in and give me 2 cents. 6 months ago I got a new job at a Solar Energy start-up. I got the interview by doing two things better than every other candidate; I had the best cover letter and I walked into the office looking great and handed them my resume and cover letter in person 2 day after emailing it in. They were already super impressed with my cover letter, so when I walked in and introduced myself, they already had a great impression of me through my cover letter, and I gave them a face to go with that resume and cover letter.
An edited version of my cover letter can be found here:
https://docs.google.com/document/d/1Pf2EgrSiogh6zDSVCoo8UzAHH61Hm1HeczIdcmOeVik/pub
I did very well in my two interviews and negotiated a $2.50 an hour raise over what they offered me.
6 months later, the CEO came to me to put me in charge of our new job hunt for a Regional Sales Executive (our company has only 5 employees, so no HR yet). I am getting to see a whole bunch of resumes and cover letters...only 30% so far have cover letters...and not one of them has been well written.
My advice:
Step 1: Put effort into your cover letter. Research the company you are applying to and make your cover letter tailored to them. Do NOT use a template for a cover letter. If you find a job you really want, take the time to make it just right.
Step 2: Show up to the company you are applying for and hand the resume and cover letter to the CORRECT person, within 2-5 days of emailing it. The idea is to hand a physical copy of your resume to the a person who has already read your (hopefully) amazing cover letter. This can be hard, it often requires extra research and phone calls, and can take multiple tries, but if you want a real chance at an interview, this has to be done.
Step 3: Give an amazing interview. This can also be hard. Either you are good at interviewing or not. If you are not, there are many places to get advice on getting better: read them.