There seems to be an emphasis on cemeteries as rich ghost hunting grounds for photographers, though many photographs are also taken at big family gatherings, such as weddings and funerals. Battlefields, hospitals and funeral homes are also likely to have spirits hanging around who haven't yet moved on. I was once in an examination room in an ER waiting to see the doctor when a spirit came in who had just passed over. I personally would try having someone talk about a spirit who had died that they loved with intensity, for in my work as a medium, I have come to know that this sort of emotional reaching out always draws spirits near. I've also become aware that loved ones in spirit continue to attend major happenings in the family, such as births, deaths, and other important occasions.
Ghosts seem to manifest in a few interesting ways on film.
The most common seems to be as orbs that are not visible to the naked eye, yet nevertheless show up on film as transparent orbs hanging in mid air. While at first these may seem easily explainable by film anomalies, after seeing dozens of photographs containing these orbs, I was convinced. Another interesting manifestation is as areas of intense light in an otherwise dark area. Swirling clouds of color and light appear in some ghost photographs, and I found this of interest because spirits often manifest to me in similar form. Some people are able to see ghosts, of course, and these people would be open to and have positive expectancy about being able to see them, and therefore would not filter them out of their perceptions.