1. Your prospective employer would need your permission before he can secure important information about you such as credit report. Some states do not allow pulling out credit reports for employment purposes. However, some information may still be available for him. He will also need your permission to access your driving and criminal records.
2. Know when to deny your permission. If he asks you about your social media accounts, you may want to allow him to do so. Anyway, he can search you on Google and he will find what pops up. But never allow him to know your password. You should apply wisdom here. It might cost you the job if you deny permission, but only you can weigh things out.
3. Find out what is available for the public. As I said early, your prospective employer can Google your name where he might find sufficient information about you. So be careful about the information that you put online. They may impact your job prospects in the future.