#1 - As a landscape, this picture could benefit from showing some sense of direction. I would recompose this shot in such a way to show foreground and background elements to add depth. The relatively straight line of the lake makes the picture seem more sterile and less organic. If this body of water was a river or stream, I'd try to incorporate it as a element of perspective by shooting the picture at one end of the river and show the other end of the river disappear into the distance.
If you were trying to make the flag the subject of the picture, one thing you could have done is to walk up to just several yards away from the flag and shoot up at the flag, aiming your camera up to about 60 degrees from ground level, and have the foliage from the surrounding trees be the background of the image. This would eliminate the ground, which is--otherwise--uninteresting.
EDIT: I just now noticed some more interesting aspects on the ground level, such as the bench and the fencerow. Because of all the foliage, it made the picture look too busy and so the bench was somewhat hidden. You might try photographing on the other side of the body of water to the left of the bench, and aim your camera towards the fencerow on the right side. This way, you can get a sense of direction of the body of water and the bench and flagpole would be much larger since you'd be closer.
If you were trying to get the effect of the reflection of the foliage in the water, I would recommend the same thing I recommend for #4. Put on a neutral density filter, set up the camera on a tripod, stop down the aperture, and take the same shot (but try to get the tops of the trees in the shot by going for a wider angle). That will eliminate very sharp and jagged water ripples in this image into a by dreamy-looking reflection that'll have a watercolor feel to it.
#2 - A macro lens would really help here since you could fill up the whole frame with the flower. But working with what we've got here, the picture looks more two-dimensional than three-dimensional. The background makes the picture look flat because it's mostly grass and it doesn't lead the eyes to any particular direction. If you could get down lower to the ground and capture the grass as it expands into the distant horizon in this picture... Some of the neighboring flowers look a little scraggly because they haven't fully bloomed yet and the foliage and stems of the flowers are also scraggly, thus detracting from the beauty of the true subject of this picture. So fill the frame with the flower in the center and don't shoot any lower than the first inch of the stem below the flower. The white balance seems off to me.
#3 - for small animals and children, I prefer to shoot pictures from their height rather than looking down at them. That lets the audience see the world from their perspective rather than from a perspective we're all to familiar with, which is from above. Could be a bit sharper.
#4 - You could have had a really great picture if you used some neutral density filters, a tripod, and stopped the aperture down a bit to get the smooth, gossamer strands of water that you see in professional-quality pictures of waterfalls. Might benefit from having the camera closer to the ground and show the fountain shoot into the sky for some sense of direction.
Study the "Rule of Thirds" and you'll learn how it's not always desirable to place your subject dead center in the picture.
