Rely on white space to define sections. Scanners like white space. They use it to determine when one section has ended and the next has begun. Horizontal lines can also be used to define sections since they are usually ignored by more sophisticated scanning software, provided they do not touch any of the letters on the page. However, avoid the use of short, vertical lines since scanners try to interpret these as letters.
Don't use columns (like a newspaper) on your resume. Scanners read from left to right and often have difficulty determining how to relate text to headings when the columns are the same width or when there are more than two columns. Although the keywords will be intact, your resume may end up looking like garbage in the ASCII text version created during the OCR process. Using a narrow column of headings on the left followed by the text on the right doesn't seem to cause the same problem, however.
Dot leaders (like this . . . . . . . . . . . . . . . . . . . . . .) can cause major headaches for the scanner, so avoid them.
One nice thing about electronic resumes is that they don't have to be limited to one page. The more keywords and synonyms you are able to use, the better your chances of being selected in a keyword search. Therefore, it is better to have a two-page resume with all of your skills and qualifications listed than to have a one-page resume with information missing because you tried to conserve space. The general rule for an electronic resume today is:
One caution, however. The reader may decide to stop reading after the first page if something doesn't entice him or her to read on. Therefore, you should make certain that the meat of your resume is on the first half of the first page.
Remember to keep your sentences powerful and interesting to read. Cyberspace doesn't negate the need for good writing. You still want a human being to read your resume sooner or later!