On my photo expeditions, I constantly encourage my fellow photographers to vary their camera height when photographing people in particular. Changing camera height to even a small degree can result in a huge difference to the background. A low angle allows the photograph to use the sky as plain background, while a high viewpoint can provide a more interesting background. The traditional technique in photographing people is to do so at eye level, as it provides "natural looking" images...but how boring! Breaking the rules and experimenting is so much more satisfying.
In the image above, I was photographing in a 'medresa', or Islamic school, in Bali and had to crouch on the ground to capture an eye level realistic image of the students horsing around while their teacher's back was turned. As photographers, crouching down and even lying down is necessary to get realistic shots. Perhaps elementary advice, and in this case a no-brainer...but I'm always surprised at how many of us still photograph children from our high vantage point.