If you believe in spirits and ghosts then you must also have a healthy dose of skepticism. Always treat noises and shadows with a grain of salt. Don’t believe everything you hear or see. As humans we have a very active imagination that takes over when we are not sure of something. Imagination is great to cure boredom or to fill time but not so great when it scares you.
If you see something that you are not sure what it was, try to get a witness to at least rule out something that can be explained easily. That shadow you saw might have an explination other than the paranormal.