A characteristic of your photograph that you really want to focus on is how your eye travels through the photograph (see what I did there?). Are they focusing on what you want them to be concentrating on? Do you intend for their eyes to wander, or for their eyes to stay focused on a certain aspect of your photo? How will you get your viewer to look at your photograph the way you want them to? Play with what you bring into focus and what you blur out. You can always blur something out later in the editing stage, if you find it distracting later on.
The first image to your left has two main focal areas. The couple, and the tree branch. This obviously took some editing, with the use of lighting. Personally, I would have edited the branch out and would have had the sole focus on the couple, but that is a personal preference.
Something to be aware of in the second image: Eyes. We, as humans, tend to go straight to the eyes when looking at a photograph. From there, our eyes will wanter. For me, I look at the woman's eyes, then his eyes, then down to their arms around each other, then her hair, then back to the eyes.
The third image definitely captures your attention with the eye of the owl peeking out. You briefly let your eye wander around the entirety of the photograph, only to settle back onto his eye, full of curiosity, a smidgen of fear, but overall, relief.
Just remember, you can take a beautiful photograph but completely miss the mark when it comes to communicating the message you want because of where the focus lies within your image.