How do I deal with being the least favorite child?

I'm the eldest child, my younger sister has always been the favorite. She gets stuff I don't, my parents never get mad at her. For example when she does something wrong they just say "everyone does mistakes, it's ok" but when I do the same mistake I get punished.
Or when she asks for something, she gets it. When I ask for something, they tell at me. And no she is not a lot younger than me, she is 1 year younger.
My parents always brag about my younger sister to friends and family, but they never even mention my name. They always tell my younger sister how kind, caring, smart and beautiful she is. I've never heard any of this from them about me.
Even my grandparents and uncles favour my younger sister. They come visit only to spend time with her.
My uncle just called my mother saying that he's coming over, because he wants to spend time with my sister and buy her things.
I just feel so left out and unloved. ://
Whenever I do something good, my parents don't even notice.
How do I deal with being the least favorite child?
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