When taking photos of subjects that either moves quickly or unpredictably, for example pets or children, it’s better to pre-focus the shot looking through the viewfinder or LCD screen. Then whilst continuing to hold the shutter button down and keeping the camera in the same position, look above the camera at your subject. When you see the moment you wish to capture fully press the shutter. This helps in 2 ways:-
1. It allows you to have a better view of the subject
2. It eliminates any delay of you seeing the moment you want to capture such as a baby smiling
Things to remember: This technique only works for subjects that remain in the same place.