It is advised that interesting shadows are created by light source that is lower on the horizon. In such a situation we get dark, long, and dramatic shadows. Go out for shadow photography when the sun is lower in the sky for outdoor images.
N case you wish to go for photographing indoors you can use a lamp without the shade slightly above the ground to have strong shadows. The closer your light source is to the ground, the longer will be the shadow. You can move around the lamp to get suitable shadows.
Try out two options by including the subject within the photo and then without it to concentrate on the shadow. At times the second option adds more mystery to the image. Also, patterns in shadows can give dramatic images. Patterns exit in every location; you need to get aware of them.
The inset pictures were taken in the morning hours to include shadows as a compositional element in the picture.