Don't start off your job search with one (or more) strikes against you by committing any of these common cover letter blunders. Each is easy to avoid, but they can sink your chances of an interview if you include them in your letter.
1. Sending your letter to wrong person, location, or department.
Do you really want your letter to land you a job at company you're sending it to? Then take time to verify that you have proper name, title and address for hiring manager or other decision maker who should receive it.
Unless you're absolutely sure you already have most up- to-date contact information, take a few minutes to call and ask. Otherwise you may as well not bother sending your letter - it most likely won't reach intended recipient. And if it does, he or she won't be impressed that you didn't bother to take this simple step.
2. Irritating your potential employer with a pushy, arrogant or conceited tone to your letter.
Are you truly God's gift to humanity? If not, chances are you ought to come across with a bit of humility, not braggadocio. Save "I am too good for you not to hire me" stuff for when you're bragging to your friends about great job you just landed. (Even they probably won't be impressed - and they already like you!) Instead, let your accomplishments and skills speak for themselves.
3. Typos, misspellings, punctuation or grammatical errors.
There's no excuse for leaving any of these mistakes in a cover letter (or a resume for that matter). If such matters truly aren't your strong suite, ask a friend to look your letter over for you. Blatant errors like these are just one more reason for a hiring manager to shunt your resume and cover letter aside, never to be seen again. Why? Because they'll think you are too lazy, too uncaring or too unskilled to be a good fit at their company.
4. Writing rambling, unfocused sentences and paragraphs.