-Store your camera in a handy place. Always know where it is.
-If you use a film camera, always make sure you have film on hand and in the camera.
-Keep fresh batteries in your camera.

Here are some pointers for when to shoot:
-Work: When your subject is concentrating, he or she will probably not notice you're taking a picture. Capture the fixed stare, the furrowed brow, the clenched jaw of determination.
-Play: Everyone has a different way of being silly. Watch for habits and how people interact with their friends.
-Emotion: Happy or sad, shy or brave, angry or glad...when your subject is caught in the emotion of the moment, those feelings make a strong impact on film.
-Secrets: Watch for interactions that reveal a child's behavior in absence of an adult.
-Anytime: The more your camera is out, the less of a novelty it is for the subject, and the less likely he or she is to pose. If your subject starts to pose, pretend you are doing something else until he or she loses interest, then go for it!