This answer might surprise you, Samarpeet, and irk others: There are no paranormal experts. One cannot be an expert in phenomena that are mysterious and that we do not fully understand. What we have, however, are some very knowledgeable people who have read, studied, and investigated various phenomena to the point where they know the background and history of the phenomena, how they have been observed to manifest, how people react to them, possibly how to deal with them, and more.
The paranormal is not just one thing. It can include ghosts, psychic phenomena, and even mysterious creatures, such as Sasquatch. And becoming an "expert," if that's what we want to call a very knowledgeable person, requires not only a good understanding of the phenomena themselves, but also at least a rudimentary understanding of psychology, sociology, physics, and other sciences.
There are no "jobs" as such in the paranormal. There are a very few people who have been able to make a living writing books or, if they are very lucky, having a paranormal-themed TV show. But such book authors must constantly be writing new books because these have a very select readership and are very rarely best-sellers. And most TV shows are very short-lived.
If you are determined to be a paranormal "expert," however, reading books is a good place to start. I suppose I would start with encyclopedia-type books, such as Jerome Clark's Unexplained!, Brad Steiger's Real Ghosts, Restless Spirits and Haunted Places, among many other similar titles that provide overviews of anomalous phenomena and many of the documented cases.
After reading through these books, you might find that you want to narrow your focus to a more specific subject, such as ghosts (books by Hans Holzer), poltergeists, psychic phenomena, UFOs, or crypto creatures. Then you can research books that delve into these subjects on a deeper level. I also encourage you to investigate the history of the subject; after all, what we do know about these phenomena is based in good measure on the research, experiments, and investigations of those who have gone before. At the same time, keep up with the latest research, the most innovative tools and technology, and current theories.
As you can see, if you really want to become an "expert," it's going to take a lot of time and dedication. Those who are the most esteemed in this field have spent a lifetime at it.
However, if you just want to learn more, read all the books that interest you, keep tabs on websites (such as this one), and maybe even join a local paranormal investigation group where you will meet people with similar interests, learn to use certain tools, discuss ideas and theories, go on investigations - and maybe have some fun!