1. Make it clear what you're offering the employer. A recruiter or HR person shouldn't have to read more than the first line to know exactly what type of job you would do at their company.
2. Don't overwhelm the reader with all your skills. Keep the resume focused and tailored for the job at hand. If you're applying for a customer service job, don't emphasize your accounting skills.
3. Define your niche. If you have a specialization to offer, you may be able to edge out your competition.
4. Play it straight. Including political affiliations, information about your personal life, hobbies, pictures, quotations, and other non-essentials is more likely to work against you than for you.
5. Keep it short. It doesn't need to be less than one page if you genuinely have more than one page worth of relevant content. If you have less than 10 years of work experience, one page should suffice (notable exceptions are for jobs in academia, science & research, and highly technical fields).