One thing that I learned recently in my marriage class is about self esteem. It think that it is interesting that most people think that they will be able to gain self esteem by doing things for themselves. Achieving a goal or receiving an award for something. But in fact it is when you are focusing on helping others that you gain self esteem. My mother has taught me many things over the years and there are many things she has taught me about self esteem. She told me recently that she is reading a book called "The Myth of Self-Esteem". The myth is that when you work on yourself to become better you come to love yourself. While in a way that may be true, the best way for you to come to love yourself is to love others first.
Another thing my mother used to tell me when I was young was to look outside myself. See who needs help. Especially in situations where I was feeling self conscious or awkward, she would always tell me that the way for me to feel comfortable was look around and see who is probably feeling even more self conscious and awkward than me. This works wonders. I can personally tell you that if you ever in one of those situations follow this advise.
Also, there is a song called "The greatest love of all" by whitney houston, (very popular song) and they lyrics talk about loving yourself before you try to love someone else and most people believe that but in my opinion, loving others is the way that you come to love yourself. I think this is really important to preparing for marriage because although you should know who you are before you get married it is through relationships that you learn to love yourself and be confident in who you are.