It is perfectly fine to reveal your first name in the early stages of your correspondence with an internet stranger. Beyond that, however, please use caution. Think to yourself, is it prudent to tell someone who you don't know, your last name, your home address, your work address or your telephone number? (The correct answer is NO). Until you feel extremely comfortable with the other person, it is best to use the USERNAME, it was designed for that purpose.
Honesty is always the best policy. Let's face it, when you are typing away from a distance, it is easy to mislead (that's a euphemism, we really mean LIE!) about yourself. Honesty breeds honesty. Stick to the truth and, chances are, the other person will follow suit.
Have you ever spoken to a business contact on the phone - and then when you met them, they looked entirely different from the way you had pictured? Exchanging a current photo (not the one taken at the beach 20 years ago) is a good way to determine whether you are attracted to the other person. But it is a good safety measure too.
It is not a smart idea to be alone with someone you have just met. When arranging your first (or even second or third) meeting with a person, make it clear that you intend to meet in a public place and arrange all transportation on your own. It is also wise to advise a friend or relative where you will be. Do not let anyone pressure you into doing anything you are not comfortable doing. Err on the side of caution and all will be well!