The only mistakes buffy made were not putting her foot down when her supposed friends would ride her ass about shit. That's it. She never did anything worthy of some of the venom she caught from people that should have known better.

And, in the case of her "escape" after her mom found out she was slaying, she should have put her foot up their collective asses day one.

Now, this also includes putting up with Angel's shit, and spike's, and Riley's.

But, she wasn't without flaws even in that context, the screenshot aside. I still maintain that most of the errors in judgement she made would have either not been made, or been made in different ways, had she better support across the board.

A lot of critics of the character forget how damn young she was, and how sheltered her upbringing was (overall). The errors of judgement she made that weren't done by having so little true support, unconditional support that took into account exactly how horrible her life became in such a short time, were made due to youth.

Think about it. Two adults in her life. A mom that she was repeatedly told she couldn't tell, and thus couldn't give her motherly support as a slayer at all. The other her watcher. A bunch of creepy old men that think they own a teenage girl, with her watcher in specific pounding get responsibility into her, even long after she'd proven herself.

That's it. Everyone else was a teenager and an idiot. Xander because he was an idiot, Willow because she was even more sheltered and naive than Buffy. I don't blame them for lacking the ability to be mature, capable friends all the time. They got shoved into things they were completely unprepared for and lacked even the advantage of Slayerhood. At first. They never gave up the bullshit attitude, though it did get less egregious towards the last season or two. But it is still the case that had that miraculously been impossibly mature and capable, Buffy would have had better support and thus made better choices.

I acknowledge that it's all the writers' fault because it's fiction, I'm treating it in universe.

So, yah, Buffy did nothing wrong. She did as well, or better, than anyone else her age in her situation could have done, and often showed a depth of character that the adults along the way lacked.