Not very many human spirits stick around like people like to believe. Think about it, if it were really a matter of not being able to let go wouldn't there be ghosts practically everywhere? People die in car accidents, disease, drugs and crime in the USA alone. With all the gang warfare going on in the streets, the ghettos and projects should be burning white hotspots for paranormal activity. It's not; this misconception that spirits of unfortunate tragic individuals hang on to a place and can't move on is all Hollywood fiction and the result of people wanting to tell a good story to get attention. Every ghost hunting show I have ever seen has always involved the cast acting dramatic in every episode and pretending to overreact to things that simply aren't there, to the point it's obvious they are making up scenarios just to keep their ratings. That being said I am not a skeptic in the fact that there are dislocated spirits, or even malevolent entities and forces wandering aimlessly. There are also beings able to visit loved ones from higher realms and watch over them. And there are beings that simply can't pass on until certain conditions have been met to purify their souls of grievous character traits and misdeeds committed in the lifetime. There are also parasitic entities whom can also be non-human which are looking for a host of life force to latch onto, or in places where they can take up residence mostly because they have been allowed to enter or called/invited to enter; otherwise they will float around until they can find something else to latch onto.
Don't worry, your natural spiritual energies keep them at bay most of the time. Just don't give into hatred, jealousy, or other lower spectrum emotions, or they weaken your barriers and allow them to creep in a little closer to do their parasitic activities. Also watch how you treat other people and animals...this can weaken barriers as well.
Stay away from people who actively like to use, befriend, and conjure spirits. They mess with elements that is common for everyone else to respect, such as the afterlife, and life itself for a reason because they have absolutely no respect for these things; therefore, they pollute their spiritual environment and yours as well. They are filled with negative feelings on the lower emotional spectrum. They are presenting themselves and their surroundings as an open buffet for these things, and as such will be emotionally unstable due to the depletion of mental and vital energies they put themselves through with these entities. Stay away from such peoples houses as well or anywhere else they reside because the spirits that follow them are able to latch on and establish themselves in said areas. They'll hang out there looking for a new mark to latch onto and feed off of. Other natural places for shadow beings and ghosts to hang out are abandoned buildings and sometimes very isolated places.
To recant some things I have said, some spirits may actually stick around if they have an unfinished message or business they still need to take care; it's not like how the TV portrays them as being fixed or helplessly stuck to an area, especially if they are not dark souls in charge of correcting misdeed these spirits move back and forth from their resting place in the higher realm. So Spirits can come and visit many places, however they will not interact as apparitions do in the TV shows with their surroundings. Keep in mind if there are places with consistent activity,you should stay away because that means that there is something seriously wrong with whatever is there, this activity can not be explained by a dead person with a grudge who was supposedly granted the liberty to stick around and make a ruckus. The explanation could be demonic even, with no human spirits there no matter what history the place might have.