Rule of thirds/power-spots.
Imagine a 3x3 grid across a photograph. The best focal points for a subject is at the intersection of these lines. If you want something in focus then you put the power-spot on the object.
The flower on this picture is on a power-spot. This makes a picture look a lot stronger than it would with everything in focus. It also helped that the flower was a lot brighter than the background so it really stood out.