User blog comment:WaffleMinifigure/Waffle's Guide to Mary Sues and How To Prevent Them/@comment-3122168-20130710232415

Good guide.

I would give two things more consideration though:

1) why Mary Sue's are unenjoyable

2) best way to avoid them

Now, as for the first, the main problem with Mary Sues is that they are so one-dimensional and uninteresting that they leave the readers bored. They're often predictable, so the reader knows that they're going to survive and that removes suspense from the story.

As for the second, you talk about giving them flaws in order to make them not-Sues. However, my main problem with this is that it oftentimes creates an Anti-Sue, which is a character who is just completely flawed and equally uninteresting to read. This is not a preferrable alternative.

Ultimately, I would suggest redefining the aim away from making a character who is not a Sue to making a character that develops, grows, and changes as a story goes on. These characters should not be black and white, as an interesting developed character is what most readers look for in a character.