While you may feel strongly that a ghost is in your home or place of business you should first evaluate each incident and look for logical solutions. Many times there may be a legitimate reason for one or more events and the misinterpretation of one event can produce the belief that all of the events were caused by ghosts. You might be shaking your head or saying to yourself, "not in my situation", but I can assure you that in many cases while the homeowner was convinced 100% that a ghost was involved there were logical reasons found that sparked the chain of events.
This isn't to say that all ghost events are simple logical solutions, but if all paranormal events were to be put in a two piles; logical explanations and paranormal explanations, the logical pile would be a mountain compared to the paranormal pile which would be closer to a pile of table salt. While this may sound dramatic (and the example is probably not accurate to scale) it is important to understand how fear plays tricks on the human mind and can force us to interpret things as being beyond our control. The most important part of thinking along the lines of finding logical solutions is to create a mindset of problem solving which will help you eliminate fear. This elimination of fear is the first step in getting any potential paranormal problems to cease.
Could the noises be animals? Chipmunks, squirrels, cockroaches, ants, and many other animals have been the cause of noises. If the noises seem random and areas can be identified conduct an honest search for possible infestation of any animal. Attics and basements are typically hiding spots for larger animals such as squirrels and raccoons.
What's that noise? While creaks and groans of houses may seem spooking they are actually quite natural. Air pressure through small openings of siding, windows, and other features may cause noises from wind as well. Pareidolia may also be the cause. In one case I investigated a dirty ventilation fan in the bathroom was the cause of "evil voices" being heard by children that seemed to come from the hallway.
Light and shadows can also fool us. Many ghost sightings of "shadow ghosts" turn out to merely be shadows created by means that we are not used to seeing. A large bird passing close by a window, a car backing into a driveway, and other lights and shadows we are not used to may make us feel as though a ghost has invaded our home. Again, once we begin to believe this then we will begin to attribute other noises and coincidences to this phenomena. By separating each incident and looking for a specific cause (or reason to believe it was merely a coincidence) you may start to see the list of potential paranormal events dwindle.
Another environmental issue to consider is EFM exposure, or the condition known as electrohypersensitivity (EHS). The reality of EHS is debated by various tests and studies, while some have verified this as a real problem others have found no connection with EMF exposure and the hypersensitivity found in many people. In my experience we have altered bad wiring or grounding in situations where people displayed similar symptoms (unusual headaches, unusual aches and pains, trouble sleeping, problems with concentration, feeling of being watched, etc.). When the situation was resolved the client noticed the symptoms went away and typically their ghost situation did as well. Whether this is a real issue or not, it is worth the try to test for bad wiring or high EMF in areas of rest or where people are present a lot. Sit farther from the TV or computer monitor, keep alarm clocks, fish tanks, cell phone chargers, and other electronic equipment away from your bedside. An electrician will be able to sweep the home for faulty wiring or grounding issues.
In late March of 2015, Clarkson University released information about a study involving a correlation between reported hauntings and indoor air quality. The goal with their study is to determine whether reports of haunting activity could be related to specific pollutants including mold in areas. These reports may be based on a toxic environment which may create psychological effects similar to reported haunting phenomena. Research into various aspects which can explain certain haunting activity is always ongoing and may explain a handful of cases at a time.