Fifty percent of the federal work force will be eligible to retire by 2010. To find a federal job, check usajobs.opm.gov and agency Web sites. Look for such things as announcements of open ings; career fairs, which may feature on-the-spot hiring; summer internships; and recruitment programs for students, recent graduates and minorities. But even while you knock on the federal government's front door, check the back door, too. How? By seeking temporary and contract jobs in federal agencies. Such jobs could segue into permanent jobs, yield pivotal networking contacts or provide experience on projects that will boost your applications.