I look at focus. Did they opt for wide or narrow apeture. Did they get the focus sharp or did the focus point accidentally fixate on something other than the subject.

I look at composition around the edge of the frame. A random branch or leaf unintentionally breaking the frame. Using something in the foreground intentionally as a frame is different. Crop out the unintentional distraction. Conversely, be aware of ears, hair, arms, hands, legs, feet, (and tails if applicable) getting cut off in the frame. Sometimes that’s a legitimate choice, sometimes it looks like an accident. Maybe better to capture the whole being and crop down later.

I look at white balance and color tone to see if it’s pleasing to me. This is highly subjective depending on the viewer.

I look for other compositional things like straight horizons, leading lines, rule of thirds. And if those rules were intentionally broken as a style choice or accidental.

I believe learners should try to follow compositional rules. Once you’ve mastered looking out for those things while minding your exposure time, apeture, ISO, and focus all at the same time when getting your shot, then you will get a feel for when you can break the rules for more impact and it still be a good photo.