As I mentioned earlier there are two basic types of hauntings, the first is called
"Interactive" and the second is "Non-Interactive".
Interactive
Interactive Hauntings are as they imply, interactive.   Ghosts in this category are able to freely move about and manifest themselves in various ways.   This type of ghost is actually a "true" spirit entity and is most likely here for a purpose.
It is this type of spirit that you will most likely be able to communicate with and they are often the easiest to remove them from your residence.
Non-Interactive
Non-Interactive Hauntings are actaully what some would call "Environmental Imprints".   This type of haunting is like watching the same short piece of video clip over and over.   The spirit in this type of haunting is oblivious to any and all types of communcication, and therefore difficult to remove.   It is safe to summarize this type as a pattern haunting.   A good example of this would be when you hear footsteps going the hall every night at approximately midnight. IN this case it might be a mother checking on her children before she goes to bed, or maybe a man coming home every night from working the 3 - 11 shift.  And thats all it ever does, over and over and over.   The activity never changes, and with little effort it is easy to determine the patterns of this type of activity, from there one can deduce the reason for the activity.
Other Factors
It is believed by some that the lunar cycle affects the intensity of haunting activities. Just as the moon affects the tides and many other processes in nature.   If you log your spirit activities you may well be able to see a pattern and plan in advance for any unwanted activitites. It is my personal belief that lunar cycles most often affect "non-interactive" hauntings, though why, remains a mystery.   In "interactive" hauntings there may be other cycles that revolve around, anniversaries, holidays or any other event that would have been significant to the deceased.