Start by googling him or her--type in his or her name and perhaps the city and see what turns up. Some dating websites will also let you contact other people who dated the person in question via that website. If you have actually met the person, you could try to get to know his or her friends, family, co-workers, etc.--they'll give you insight into the person. If you haven't met the person and you're feeling anxious, then 1) you should think about why you're feeling anxious. Has the person made you nervous in some way, or are you just uncomfortable with the idea of online dating? Trust your gut. 2) If you decide to meet him or her, do so in a public place. Don't exchange phone numbers or addresses or even give your last name until you feel comfortable sharing that info. Online dating is usually safe, but not always--protect yourself.