Also, if you forget their name when you see them again, don't be embarrassed to ask their name again. It happens to the best of us. Speak to communicate, not to impress. No one wants to be around a downer. One of the most important things to do to have a powerful first impression is to get the other person to talk about themselves.
People generally enjoy talking about their interests.
Depending on the situation, think in advance about the types of questions you would like to ask. Keep in mind it is important to always speak to communicate not to impress. By becoming sincerely interested in others, often you will build great rapport and will be remembered. Suspend judgment and withhold assumptions. Make the other person feel as if she or he is the most important person you will meet today.