demons

http://www.deliriumsrealm.com/delirium/demonlistA-E.asp
give this site a try, it has alot of info, most of it is still explained only from one side of a religious paradigm, but it will still serve to help you gain greater understandings on demons.
Personally i have had encounters with lilith, and from my own experience she is very much a real, and pretty primal demonic entity at that, as Akylos mentioned rather start at lesser demons and work your way upward, just because as you do you will learn heaps, each lesson in turn will serve to benefit you again later on along your journey.
Also, one can visit hell via projection, not astral hell nor hell within mindspace but the actual etheric realm, but to do this specific levels of energy, release, respect and understandings is required, but well worth the effort when one wants to find a true mentor to assist and guide you along your path.