Shake hands with her parents, look them in the eye and say hello. Smile to show you are glad to meet them. Showing a little nervousness at the first meeting may actually make them like you more, as this will indicate to them that you regard the meeting as important.
Be polite. Always call her parents by Mr. and Mrs., until they correct you and ask you to call them by their first names. Ask them how they are and engage in some small talk.
Avoid swearing or using slang words. Use as much formal language as you are comfortable with. After all, you are trying to impress them with your suitability as a boyfriend. You want to sound as intelligent and educated as possible.
Compliment something about their house or the meal, if you are eating with them. Pick something you sincerely like because her parents might recognize an insincere compliment and think you are untrustworthy.
Ask questions to show you are interested in the family, when the opportunity arises. For example, you could ask her father if he likes a particular sport or ask her mother if she is interested in art, if that is the topic of conversation.
Offer to help, if it is appropriate. This is appropriate only if an extra pair of hands would actually help instead of getting in the way. For example, if her father is unloading heavy items from a car or her mother is laying the table, you could be of assistance, and it would give you something to do with your hands.
Never interrupt her parents when they are speaking and avoid disagreeing with them, even if their views are opposite to your own. You don't have to agree, but you can avoid disagreeing. Remember they are interviewing you for the role of their daughter's boyfriend.
Avoid bringing up controversial topics such as politics or religion, because her parents might have strong views and this could lead to arguments.
Compliment your girlfriend during the conversation to show you hold her in high regard.
Don't bring aspects of your life or your personality into the conversation, if they do not show you in a good light. For example, if you were caught speeding that morning, this information should be kept quiet unless your girlfriend brings it up. Then at least have the decency to look ashamed of yourself.
Thank them for the meeting at the end of the time together.
- Ask your girlfriend beforehand what her parents are interested in, so you have a head start on conversation topics.