Always be humble, kind and helpful towards your sister. If you are young now, you might be having frequent quarrels with her, but remember they can be very helpful in giving advice. It is proven fact that girls are good in giving advice. Be friendly and nice to them, tease them but not to the extent of ending up fighting like wild dogs. Share your secrets with them, let them feel comfortable to share their secrets with you. They will be very helpful to you if you have any family issues, love relation issues, etc in your life.