There's a saying among photographers that "moment is everything." This means that good lighting or composition doesn't mean as much as capturing the moment that should be captured. David duChemin countered that argument in his podcast by reminding everyone that the composition of that "moment" can make or break the image.
I recently took two photos of my four year old on his scooter. In my eyes, one image is more compelling and powerful than the other. Let's see why.
This definitely is an image full of (silly) emotion and some movement. Can't you see the lines in the road pulling your eye toward him? He's centered in the image which creates tension for the viewer. If I didn't have the second image (below), I'd be tempted to make this the keeper image. However, let's see why I picked the other shot.
So, his tongue isn't hanging out. Doesn't that take away from the emotion? But look here. His body language is more active. His feet are even about to lift off the ground like he'll scooter away any moment.
Let's also see what I as the photographer did to make this image more compelling. I pushed in a little bit, getting the viewer closer to the action. I also got the camera closer to the ground. This makes the viewer feel the moment a bit more. You can also see that he's standing just in front of a band of light. In Image 1, that light band is a bit distracting and I wish he was standing inside it. However, in Image 2, by pulling my camera down, that the light band is thinner and not as distracting.
Tips for making the most compelling image
Start with grabbing a few shots of the situation. Then consider if by moving your camera or body, could you make the image better. What if you got closer to the ground? What about higher? Can you adjust your aperture to blur out distracting elements? Could you make the light more interesting by shooting into the sun or finding a cool shadow?
Point is... when you think you've captured a "good" image, don't stop there.
Look for a better image. That will make you a better observer of light and of the world around you.