Tip: Font Size
A big mistake a lot of resume writers make is that they shrink their font size when they add something new. Yes, you want to keep everything on one page, but never go under 11 point font to do so. By definition, if you have something "new and relevant" to add, something else has just become "more dated and less relevant", and can be minimized or deleted.
Tip: Resume Length
Generally, after about the 10th year of your career, you have enough relevant information to justify extending your resume to a second page. Mine is a page and a half.
Just make sure that you scrutinize your dated and less important information in the same way that you did when you were trying to fit things onto one page. If the details of one of these older sections have become fuzzy and unfamiliar"so that you cannot defend them during an interview"they should not be there.
A well-organized resume suggests a well-organized worker!