Necromancy is working with spirits. That's it. Working with spirits. I would not call it a forsaken art. If you call on your dead grandmother and petition her for her help, you are practicing necromancy.
I wonder why it gets such a bad, spooky rep in pop culture?
There can be other facets to Necromancy besides interaction with spirits. Just working with spirits, contacting spirits, or speaking to the dead is done often by mediums. And most mediums do not consider themselves Necromancers.
Additional facets of the Art include: interacting with the Energy of Death for spells, Entropic meditation, visiting the Realm of the Dead, interacting with the "life energy" of others, healing/harming, interacting with the dead, creating serviators of death energy, and generally observing how Death interacts with our lives. Some are also known to worship or attempt communion with the various entities that are known to embody death.
The Art is much deeper then first glance shows, like any magic
Necromancy is considered much more dangerous than other types of magick for obvious reasons. I've heard stories of people getting stuck in death when working there. if you want to try it, stay away from death until you know higher magick.