You first need to agree on a day that you will come to the parents of his girlfriend. This process should not occur spontaneously. After all, the girl's family should be given time to prepare a festive table, and you can't live morally, and to make all necessary purchases.
In any case you can not come to propose to the girl with empty hands. By tradition, the groom must bring his future father-in-law a good strong alcoholic drink. For such a case fit whiskey or cognac. And his future mother - in-law a beautiful bouquet of flowers. The engagement ring as well prepare in advance and take it with you.
After all the family members will settle down at the table, stand up and ask with words. On names-patronymics contact with words to the parents of his girlfriend. Tell them that you love their daughter permission to marry her. If they will give you a positive answer, then take out the pre-cooked wedding ring and put it on the finger of the bride.
If the bride's relatives know you are, then get ready to answer their many questions. You can pre-think answers to the most common of them. For example, the following: who are your parents, where after the wedding you're going to live, how you plan to provide your wife and how you relate to the children.
Try to leave about itself the most pleasant experience. Be courteous, neat, attentive. Willing to answer any questions the family. Do not allow yourself liberties in relation to girlfriend: don't kiss her at all, don't hug. Because some parents may not like it. It would be best just to hold her hand.
You must learn the names and patronymics of all relatives of the bride. Otherwise you risk to get in an awkward position.