Can some one give steps to win your dream girls heart who is your best friend James non identical twin sister?

Ask your best friend James what he would think about it. He might like the idea, or he may not, but you will not know until you ask him. Whatever his opinion, it is your decision if you want 'to win' the heart of your 'dream girl'. If he is okay with the idea of you dating his sister, then there is no problems and nothing in your way regardng him. However, if he does have a problem with it, then ask him why and see if you can reassure him or maybe change his mind. Some brothers can be very protective of their siblings, especially sisters. At the end of the day, it is yours and the girls decision if you want to be together, but be aware that your friendship with her brother may be on the line.