I put a lot of effort into formatting of resumes. After you get your basic content correct, I recommend putting a lot of attention into the formatting. Look at spacing, font size, readability, margins, indention, etc. Especially make clever use of line spacing, bullets and bolding. I recommend avoiding underlining and italics if possible.
Basically, section titles (ie – Professional Background, Education, etc), company names and job titles are the first thing you want someone to see upon initial glance. So these should be bigger and bolder than the rest of the text. At the other extreme, the actual years of service at a particular company (ie – “1999 – 2003”) is one of the least important pieces of information, so it should carry the smallest font size within the document.
One other trick is to hold your resume at arm’s length to see if the important section titles and information are readable and easily discernable from the rest of the resume. Also see my related post explaining a “quick-glance” test related to identifying formatting problems.