SELF CONTROL
Learn the art of enjoying a woman's company without sex while you're unmarried. If the only thought that comes to your mind when you're with a lady is SEX, then you ain't ready for marriage because marriage isn't even about sex. Even in marriage you can't get sex every time you want; sometimes your wife will be sick, or far from you, or just gave birth and will need months away from sex. What will become of you then?
Learn self control now. Marriage doesn't solve lack of self control. It's tougher in marriage. Learn to control yourself for your own good.