When it comes to the job search, I've often said that most people stand or fall on the basics. MSN Careers has a great article on 25 of the basics. Some of my personal faves are:
7. Typos. Sending a cover letter or résumé filled with grammatical mistakes and typographical errors shows hiring managers you don't care about the quality of your work and probably not about the job, either.
9. Focusing on yourself and not on the company in the cover letter. "When 'I' is the predominant subject – and there are times when it is the onlysubject of all the sentences in the cover letter – it indicates to me that they don't understand my organization and its needs, and, in fact, says they don't care to know," says Dion McInnis, associate vice president for university advancement at University of Houston-Clear Lake. "And therefore, I don't care to know them."
16. Not researching the position. Your chief objective in an interview is convincing the hiring manager you're the best candidate for the job. How can you prove your qualifications if you don't have an idea of what skills you're expected to have and what your responsibilities will be?
19. Forgetting you're being interviewed from the moment you walk in. Just because you're not sitting down at a desk across from the hiring manager, don't think you're not being evaluated. For example, employers will often ask their receptionists if you were nice to them.
You can read the rest of the article here.