I said I was gonna do this so long ago, but I never found the time! Well, no time like the present!
Like Debate Etiquette Tips, I just wanna list a few important guidelines for objective story critique and invite everyone to contribute their own! It's a good thing to think about.
1. Read the story
There is no shortage of people who think they can critique a story when they only read half of it. Or half a chapter. Or half the summary. Or they didn't read it at all but they know the author, and, well, it just sounds bad.
NNnnnno. That's not allowed. You don't get to pretend to give an informed opinion on something you actually know nothing about. Read the material, THEN form judgments.
Although, I think there's leeway when it comes to special cases, like if you didn't read the book series but you watched the movie adaptations. If they're similar enough, you can use them as a basis for your opinion of the universe as a whole. Just a BASIS, though.
Besides, a movie adaptation is often a narrative of its own. You can say something like, "I don't know how it went in the books, but in the movies this character's development was handled rather poorly." That's a fair and valid statement.
2.Your world isn't THE world
"Before making judgments, ask other readers what they think, especially those coming from other cultures. You may be surprised to see how their reactions differ from yours." -Me from the past
If you're a fairly open-minded/educated person, you may not need to do this. Some people don't have trouble imagining how something that's taboo in their community could be okay in another community, or vice versa.
Unfortunately, many people do. :[ And if you're one of them, you've gotta take whatever steps are necessary to keep your biases out of your critiques. If you find yourself saying something very definitive or damning, like "this character is unrealistic" or "this character is wrong", step back and ask yourself why you're saying that. Is it because what they're doing doesn't fit into the story's universe, or is it because it doesn't fit into YOUR universe?
Get help from other people if you need to. The hardest place to escape from is the confines of one's own mind.
3. What you like doesn't actually matter
This is kind of an extension of #2. Not only is a story NOT required to apply to your reality, it is also NOT required to appeal to your tastes. You are not the one true judge. Just because you don't like a story doesn't mean that it's a bad story. That is why this topic is about "objective" critique.
Is there such a thing as truly objective literary critique...? I don't know. There may not be. But we can at least strive to be as objective as possible, and by that I mean striving to make a story into the best version of itself. Not the best story ever, not the best example of the genre. The best version of itself.
4. Watch your words
"In the world of literature criticism, words like 'flat', 'boring', 'uninteresting', 'strong' (as applied to story) ARE objective terms, and you actually DON'T have the right to fling them around as you please. It's like calling a researcher's study 'untrustworthy'. If you don't have a legitimate reason for saying that, you're basically just slandering them. Not cool." -Me from the past
So, yeah. Learn the definitions of the words you're using to talk about stories, and use them correctly.
"Flat character" does not mean "character I don't understand".
"Weak character" does not mean "character I wouldn't enjoy writing".
These words have largely agreed-upon meanings; they're not just insults! Do some research if you don't know.
5. Be suggestive~
Good critiques often include suggestions. A critic that actually has something to offer tends to look more credible, after all. AND it's easy to judge the objectivity of your critiques by examining the suggestions you give, or might have given.
Do you often suggest that entire characters be removed? You're probably not being as objective as you could be. What that sounds like to me is a knee-jerk "Ew, I don't like that, get rid of it" response. Many kinds of characters can work in a story, even if it doesn't look like they could on the surface. It would be better to suggest ways in which the involvement of certain characters could be scaled or modified.
Are your suggestions supported with lots of "I" statements? "You should change that character's reaction because I don't like how..." "I've seen lots of people do this, so it would look..." Again, you're probably not being as objective as you could be. Your experiences as a reader are NOT invalid, but they're also not the be-all and end-all. Which brings me to the last item on my list...
6. Read a lot!
You can't be a good food critic if you've only ever eaten your mom's cooking. Likewise, you can't be a good story critic if you only ever read certain kinds of things. This is probably the golden rule of any critique: expand your horizons!
The more you read/watch, the more you learn about what does work, what doesn't work, and what just needs a little work. You also learn about how things are seen by readers over time, and how things will be seen upon publication: maybe it's not a good idea for Author #2987 to tout their story as a groundbreaking, never-before-seen idea when it's actually incredibly similar to something Author #14 did, and Authors #27-60 parodied. ^^;
Mmf, that's all I got. This was a really hard list to make...I hope other people can give more and better guidelines. :]