Ghosts are usually non-corporal entities which were once human and are no longer among the living. Those ghostly manifestations take on several different kinds of hauntings and may or may not actually be the spirit of a deceased person. Most often the kinds of ghostly phenomenon witnessed by individuals is a residual. It's not actually a spirit of the so much as an impression left on the location by an event which happened there. This event could be something as mundane as the canning done ever fall which carried some sort of significance for the individual doing it or even merely walking up the stairs. These sorts of events are benign and not all together uncommon though individuals not use to encountered such phenomenon may be spooked by such events. More uncommon are the impressions which carry some sort of strong emotional energy such as anger or despair. These are the hauntings most commonly heard about as they make for good stories though these events can be from events ranging from someone under constant abuse to a grizzly murder. Again such instances are usually benign though disturbing to the people experiencing them. Unless this is also accompanied by physical phenomenon these are never hazardous to the individual in the presence of them, so remain calm and you may find yourself gaining information regarding the events which once took place. Then you have free ranging spirits of the dead, True Ghosts.
True ghosts are aware and can act in any number of ways. Some can see and interact with the individuals around them while others will not be able to tell there is anyway else around. These entities are almost always scared, angry, or filled with other strong emotions surrounding their deaths. These spirits range from the completely benign or even beneficial watching out for children and sometimes keeping more malevolent entities at bay to being completely malevolent and despising those still living. The later variety are rarer thankfully but can be most dangerous.
Before deciding on a course of action for a haunting, it is first necessary to determine what kind of haunting is occurring at the location. Look for repeated events at specific times of day or even specific times of year if the known haunting has been occurring for long enough. If the events are almost all repeated events with no real change to pattern then it's just an impression and much easier to deal with if it has become bothersome. The hauntings people need to concern themselves with most are the ones which it is apparent the ghost is not just a cyclical haunting but a free roaming entity. If it is a free roaming entity, has it made any overt moves to either frighten or harm the people at that location? Does it manifest itself as a feeling of uneasiness or being watched? Does the location grow cold when the spirit is present? Has it ever made a physical manifestation and if so does the manifestation bring with it a feeling of dread or horror? These are all questions one needs to ask before deciding on a course of action. The more powerful the entity the harsher the methods one will have to use to be rid of the entity. Also depending on whether the entity is benevolent or malevolent will make deciding what course of action to take as well. If the entity is benevolent, try talking to it. Sometimes just the acknowledging of it's presence can make it seem less threatening or scary if it hasn't made it seem like it was seeking to harm anyone before now. If you can find someone who can act as a medium for the spirit they may be able to show the spirit to the light and the peace that waits beyond. For spirits which are of an obvious malicious nature it will be necessary to force the spirit out and banish it to whatever realm awaits for it.
When dealing with hostile entities, you need to determine what they are for certain. Those which were once human may be hostile or even scary but they do not give off the same feeling as something demonic in nature will. If it feels like a pervasive evil bent on destroying the household or a specific individual then most likely you are dealing with a demonic entity and will need to approach this in a very different way. Trying to approach a demon in the same manner you would a hostile ghost will only anger the demon and make things worse on the people at the location of the haunting so proceed with caution.