Here are four mistakes that hinder most resumes. I see them over and over again in the hundreds of resumes I review each year from prospective clients.

1. Errors in spelling and punctuation.

This is the most common (and deadly) error!!! and your spell-checker is not enough.
You must read through the resume once for accuracy (numbers, dates, city names, etc.), once for missing/extra words, and once more for spelling.

Then, show your resume to several friends and ask them to read it out loud. Listen to where they pause; this could mean you've written something confusing or inaccurate.
After you get their feedback, revise the resume so that it's 100% error-free.

2. No objective or summary.

By not choosing what job you want to do, you start your resume off on the wrong foot.
Why? You force the employer to read it all the way through to figure out what kind of job you're suited for.
You create more work for your busy reader. This is the last thing you want to do!

3. Focus on responsibilities instead of results.

While it's important to tell the reader what you did at each job, it's far more important to spend most of your time talking about what you accomplished and how you made yourself valuable to past employers.
Focus on results and achievements. The more specific, the better.

4. Too many big words.

It's a shame how often a resume is ruined when the author utilizes a superabundance of polysyllabic terminology, or uses too many big words.

Don't hide behind your vocabulary. When your resume is not clear and to the point, the reader gets bored, time is wasted and your resume goes in the trash.

Simplify! Write as if you were talking to a class of sixth grade students. That's the reading level all journalists are trained to appeal to in their writing. If it works for America's newspapers, it ought to work for you.

Instead of saying "implemented", try "adopted" or "set up", for example. Never "utilize" what you can simply "use". Don't "interface" with people; "work" with them. And never use "impact" as a verb. (Meteorites hitting the moon are about the only thing that should "impact") Use "affect" instead.