Unsurprisingly, critiques are an important part of this site. You have to crit the works of others before you can even post your own and the tit-for-tat system encourages reciprocating ones you receive. It's the lifeblood of the website that allows us to have a mutually beneficial exchange. Despite this, it may be an overlooked part of the site.
Let's face it: most of us sign up for the site because we want feedback on our stories. We're authors looking for valuable input in order to improve our writing. That is the focus—the 'good part'. It's easy to forget about the part where you help others the same way you want help. Actually, it's not just that. The bigger problem is that being an author doesn't automatically make you a skilled critter. You can be the best author in the world and yet not know how to give good advice to others. This is something that may become apparent after using this site long enough. There are many wonderful, well-meaning people here, but not all give the best advice. That's why I'm here to help.
So, what makes a good critique?
Constructive Feedback
The first thing to make sure is that you're being constructive in your feedback. This one may sound obvious to some, but not everyone understands this principle. It's easy to point out things you don't like and be negative about it. It's harder to offer meaningful advice to improve. No one wants to just read you complain about everything they wrote and offer nothing.
Instead of telling someone "this paragraph is boring", think about how you, as a writer, would freshen it up. Offer some suggestions on ways it could be more interesting. Just saying that something is bad is discouraging. It's important to leave a path to making it right visible to the author.
Even if the story isn't in a genre that interests you, that doesn't mean you have nothing of value to add. I don't ever read Romance stories, but I ended up giving a return crit to one and found something relatable that I could comment on. It's just important to keep in mind the genre when critting. Be upfront if the genre isn't one to your tastes, but also give the author leeway if what they wrote makes sense for their target audience. If they're writing sci-fi and that's not a genre that interests you, you probably shouldn't criticize them when going into technical details loses you. It's sensible that this genre will touch on technical terms. It's important to have some basic genre savviness, even if you don't read that genre. If you're unsure, a quick Google search can likely clue you in on the common tropes and structure of a specific genre.
Also, don't forget to praise things that are done well. When critiquing, it's instinctual to point out all the problems in someone's work. This can be very disheartening, as it leaves the impression that there was no good, and only bad. It's important to also tell people the things you like. What did they do well? This not only helps encourage the author but ensures they don't accidentally delete the good parts when they revise.
Consider Context/Intent
Many things can read very poorly out of context, but make sense in the right light. Sometimes you have to give the author the benefit of the doubt. This is especially true if you come into a story late and haven't read previous chapters. Just because something isn't explained in that chapter that you're reading doesn't necessarily mean it was never explained. Let's say you see a new character introduced and the author does a good job describing and setting up that character. You can assume the author knows how to introduce characters and concepts into the story. So if you later see another character with no introduction, it's probably not a good idea to get on their case about it. That's almost certainly a character a reader following the whole book should already know.
If you don't understand something right away, it's fine to make a note of it, but if it becomes clear later on, you should also state that as well. Too many times, I receive crits where someone complains about a lack of information and said information is given in literally the next paragraph. It's good to be patient and allow a story to unfold before claiming an error was made. And if you do figure out what the author was going for later in, it's nice to let them know. It can be annoying to an author to have people complain about things that are explained in the same chapter. At least acknowledging that the author properly addressed the problem will alleviate that.
Sometimes critical thinking helps. If something sounds off to you, first try to figure out what the author meant. Try to get in their head and see if you can make sense of it. This can be a good exercise that will improve the quality of your feedback. It reads a lot better to say "Hey, I think you were going for X but it comes across as Y to me." This is better than just insisting that the author wrote Y.
Make Sure You're Ready
Because of the tit-for-tat and Super Critter goals, some people might start thinking more about quotes than the human element of critting. It's important that you're in the right mindset before you begin. If you're not feeling it or are distracted, you're going to type something lower quality than you probably wanted to. Once you submit, you can't go back and change it. Make sure what you're submitting is what you want to send. If you seem flighty or not really paying attention to what you're reading, your crits will come off as unreliable and may be dismissed even if there are good takeaways mixed in. It's important that the story has your full attention when you're going over it. Anything less is doing a disservice to the author.
Don't forget that CC has an autosave feature. If you get interrupted mid-crit or are short on time, you don't have to push it through. Just come back and finish later. Only submitting half a crit because you had to go can come across as disingenuous. Since you can resume at any time from any device, there's really no reason why you can't come back to it and finish.
Have Some Fun
You're not writing a book report for school, so there's no need to be stiff and formal for your critique. Imbue your personality into it. There's nothing wrong with human interaction. React to scenes that stand out. Maybe you found something funny, so you throw in a laughing emoji. Maybe you feel for the character when something bad happens, so you comment "oof". People do enjoy reading genuine reactions to their works. While the bulk of your submission should be focused on helping them improve, reactive comments are still a form of feedback. Most authors I know (myself included) love hearing theories and predictions on where the plot is going, so if you feel inclined to make those, go ahead and throw them in there. You want your critiques to be uniquely you. And really, if you can't have some fun with it, it'll become a tedious chore.
We're all here to help one another and the more helpful we can be, the better and more useful this site becomes. Here's to becoming an outstanding critter!