Answer all their before-the-first-day questions. Where do I park? How do I dress? What forms of ID do I need for paperwork? Put them at ease and help them walk into their new jobs with confidence.
Securely distribute all the required forms and documents—W-4, I-9, employee handbook, etc.—and provide a support channel for any questions that may come up after the initial meeting. You can also create evaluations for compliance.