If you are lucky to have a sister, then you understand the blessings of the bond you share with your sister. On her special day, make her feel special as well. Greetings for blessing should mark on the birthday card showing love and respect as you say to your wonderful sister a heartily birthday wishes. Wishes can be implemented as you say for your best friend because a sister is more than a brother's best friend. Start writing with respectful remarks and joyous feelings for her day.