I've spent a fair amount of time over the past 12-18 months reviewing resumes and conducting interviews with people applying for various positions at my company. In that time period, I've been pretty shocked at the quality, or rather the lack thereof, evident in the submissions I receive from many people. Your resume and cover letter is the first thing I'm going to see about you as a prospective employee at my company. It is from this information and how it's presented to me that I will decide whether or not to spend more time conversing with you, up to and including a face-to-face interview. When you consider the fact that: 1) I have other responsibilities on the job outside of hiring, and 2) I have a lot of resumes to go through, it would seem to follow that while your resume isn't going to matter much once you've got the job, it's the single most important factor prior to that event.
With that in mind, here's some advice to the job hunters out there. My advice is being given from the perspective of a small, technology oriented, Web-based business.
Only put important things in your resume
There are few things I dislike more than receiving a 6 page resume with 4 pages of various contract jobs, and 2 pages of certifications, qualifications, alphabetizations, balanced equations, and chemical formulas. My eyes are going to glaze over and I'm going to remember your resume simply as being "that long one". If you've got a long work history, then give me your last 5 jobs or 5 years of employment. If I want more beyond that, I'll ask for it. If you've worked in retail or the food industry, I don't want to read about it unless you were management. The ideal resume is one page in length, contains no "filler", and reads like a list of reasons I'd be stupid not to hire you (instead of a bunch of cobbled together notes loosely tied together).
Spell check your resume
Why do I even have to mention this? The number of spelling mistakes I've seen in resumes is astounding. Yes, I understand that when you apply for a technology oriented job, Microsoft Word is going to put a red squiggly line under every protocol, programming language, certification, or industry acronym you type out. That does not mean you should assume you can ignore every one of them. If I see you've misspelled Cisco while expounding upon your proficiency in configuring Pix firewalls, I'm not going to think too highly of your attention to detail. Misspelling a word is the most easily avoided mistake. Along those same lines...
Try to avoid using webmail services
I don't have any problem with someone using Yahoo, Hotmail, or Gmail when communicating with me. If that's your preferred email account instead of your ISP or university account, I can accept that. The problem is that unless you're using Mozilla Firefox 2.0 as your browser or composing your messages in an external editor, you're prone to spelling mistakes in your messages. When I'm doing a preliminary interview through email with someone applying for a customer service position that uses email to fulfill the majority of their duties, bad spelling and grammar is a poor reflection on your qualifications for that job.
Research the company
One of the first things I ask applicants is whether they've heard of our company and its products. If you haven't, the correct answer to this question is not a simple, "No." The correct answer is "Not until recently when I saw your open position. Since then, I've checked out your web site, downloaded your products, tried them out...." and so on. You're looking to start a career with a new company. Some people look at jobs as a necessary evil. I don't want to hire one of those people. The type of person I want to hire is interested in the work they do and it matters what kind of company they do it for. If you can't be troubled to learn something about the place you sent an application to, I'm going to return the favor and skip putting forth the effort to get to know you. The more you know about my company beforehand, the better you'll be able to impress me with your ability to relate the questions I'm asking you to operations of our business.
The interview is a two-way street
Obviously, the primary goal of the interview is for you to sell yourself to me and convince me that you're the best candidate for the job. However, and this ties in to my previous point about researching the company, I like for an applicant to come to the interview prepared with questions for me. I don't care what you ask me as long as it's relevant. You want to ask about the growth of the company over the past 5 years? Please do. Do you want to know about the long-term goals of the company? I'd love to tell you about them. I don't like it when I get to the part of the interview where I ask if you have any questions for me and the best you can muster is "How long is the lunch break?" This again shows a distinct lack of interest in the company, the job, and the culture surrounding it all. From the moment you first step foot in our offices, there should be a dozen questions bouncing around in your head that you're dying to know the answers to before committing to making a career with us. Share some of those questions with me and let me know just how serious you are about your career.
While I stated that my advice comes from a specific perspective, I think this advice is applicable to most jobs in general. This isn't rocket science at work here. But it is your livelihood, and through our potential connection as co-workers, my livelihood at stake as well. The effort you put into creating your resume and researching my company prior to the interview will be evident to me. If you're serious about the job, then that's exactly what you should be striving to achieve.