If you suspect or are experiencing what you think may be paranormal activity….

Remain calm, remember all you can of the experience, write down the details as soon after the event as possible and try to discover possible rational explanations.
As real as some of these things might seem, there could be completely understandable and ordinary reasons for the occurrences.
Keep a journal of phenomenon as they occur.  Include as much information as possible.  

Example:   01/15/05  raining  10:30 pm  Just went to bed and the bathroom light turned on.  I was alone in the house.

Noises:  Attempt to record them with a portable tape recorder
Physical phenomena:  Attempt to photograph or videotape them
Keep the journal, recording and camera equipment available in the location where most phenomenon is occurring so it can be documented as it happens. This evidence will help with any formal paranormal investigation.  (Times are very important because that helps SPIA decide on the time to perform the investigation.) It may be easier for you to send a daily email to SPIA of the occurrences.