Shadows are all around you, the harsher the light the better defined the shadows will be and give you more interesting subjects and the best they are all around you, just look down or to the side.
Look for shadows that interplay with each others are shadows that creates stark contrast. Shadows are perfect subjects for black and white processing, but can create very interesting items even in color, especially when paired with muted colors.
The tricky part to photograph shadows is to nail the exposure. Using any auto exposure mode will lead to an overexposed image, the cameras light-meter will try to compensate for the dark areas and lighten up the picture and bring out details in the shadows.This is of not what we want, but nothing that we couldn’t fix in post processing right? Sure, you could but why not nail it directly in the camera and minimize the time in your digital dark room. To control the proper exposure in shadow photography it’s best to stick with manual exposure mode, make sure your histogram is pushed to the left.
Afraid of manual exposure mode or just want to do quick adjustments on the fly, just dial in a heavy Negative EV exposure compensation instead and be done with it.