Photography is, ultimately, an act of selection. You might hire a model or set up a still life, but then you select. This is why, unreasonably often, the first crop is the best. By cropping and re-cropping you begin to enter the world of digital art which is something else entirely.
All photographs are of course more than a simple selection of things to frame, there is always some sort of postprocessing that occurs. Still, the more selection and the less tinkering after the fact, the more it looks like photography and the less it looks like some sort of drawing.
In an ideal world, when you press the shutter button, you have a fully realized previsualization in your head, which you then simply execute to make the final print. In reality not so much. For good work, though, it's fair to say that the photographer often or usually has a fairly clear concept in mind. If not, then this artist isn't really doing photography. This artist uses the camera to generate raw material for digital art. That's a thing, and by no means a bad thing, but it's not photography.
It is for this reason that the most common sort of critique we get from fellow photographers is so insulting. The vast majority of photographers, when asked to comment on another's work, won't. Instead they will chatter on about other pictures, pictures they would have made. Frequently, in fact, they will insist on demonstrating their Photoshop skills, or lack thereof, and render some different picture. They will completely ignore the actual photography, the selection part of the process, and will work instead on making something new and different.
In short, they refuse to acknowledge the original picture except to imply that it sucks because it's not the picture they would have made. They will insist instead on talking about other pictures, their own, and finally they will insult you by doing some digital art loosely based on your photograph to show what they mean about how awesome their picture would have been if you hadn't fucked it all up with this terrible starting point.
Consider the kind of critique we get from non-photographers:
I like it!
I don't get it, what is it?
What a sad picture, it makes me cry.
I don't like black & white.
I love the shadows!
Compare with the kind of critique we get from photographers:
The white balance is wrong.
I would have put a hair-light on her.
You should clone out that thing, let me show you
Have you tried it in black & white?
An actual artist is likely to circle back around to what non-photographers say, but perhaps with some explanations and discussions of artistic intent and methods. Only the photographer spends all this time on dumb technical choices which you have already made, and ignores absolutely everything about whether the picture is any good. The photographer focuses mainly on rendering issues, mostly ignores the subject, and apparently doesn't know that the idea or meaning might even exist.
A photograph is what it is. When I show you a picture there is very little about it that isn't there on purpose. When you show me a picture, I assume the same is true unless you specifically state otherwise. What I want to know is not what your pictures are like. I'm sure your pictures are very nice, but what I want to know is how this picture right here works for you.
Yes I'm sure Romeo and Juliet would be much better as a rom-com and I see that you don't like sad plays. Please stop writing a comedy about Romero and Julie, I don't care. Please stop.
In the absence of request for some specific kind of response, the only respectful kind of critique is whether the picture works for you, how it works, how it makes you feel, and perhaps why you think it makes you feel that way. If you don't get it, say that. If you really think you get what the original photographer was going for, and you see a way to get at that better, maybe a little editing is in order, but only if you're pretty damn sure you're in the artist's head. Don't waste the artist's time talking on and on about your own damned pictures.