To become a good paranormal investigator, read, read, read! I would recommend books such as the Encyclopedia of Witchcraft and Demonology to get a background of how that end works, and then I would read the Demonologist for some case study files. Start building your library, then seek out a local ghost group and see if you'd like to join them. Make sure you quiz them on their beliefs so you're all coming in from the same angle. I have some pages on my website that might be helpful to you; www.phantasmpsiresearch.com. Hope this helps, and good luck!