How to avoid a mary sue character?

-I see the term Mary Sue tossed around A LOT nowadays. I try and make characters believable and real, but with some exceptions depending on the story. Like, for example, I have a character that can see spirits and stuff and has been annoyed by them a lot her entire life. I don't really think she's too mary sue, I guess, but I would love some input on how to avoid making mary sues still, so I can edit some of her information. C:Whether a character is a Mary Sue depends on whether she has flaws. Saying "She can see spirits and has been annoyed by them" is an ability - not a virtue or a flaw.



If the character is beautiful, smart, talented, and everything the author wishes she could be, that's a Mary Sue.



If the character is (for example) kind of naive, or not thought of as particularly beautiful, or lazy, or tends to ruin everything she gets involved in - those are character flaws, and that's not a Mary Sue.