Okay, from what you've said Mr Doorman ( :D ), this ghost is really just a normal ghost that wants to be alone and doesn't really mind you, your pets or talking a little.
Basic facts:
-Don't bug it every while. The ghost/soul will get pissed.
-Try to ask why is it a ghost, because more likely ghosts exist because of some way they died or something in their lives made them stay in the physical world instead of going to heaven/hell.
-If the ghost/soul is trapped in some way in the physical world, ask it if he/she would like help to get to heaven (Because staying on the physical world is pretty much like being stranded on an island.)
-If he/she would like to get help into heaven, contact a priest.
-To even help the ghost better, ask what church he wants.
Also, you may want to leave taperecorders on around the house when your away or something, because they can record things we can't hear. Also, video cameras can catch things we can't see. Obviously, you should know these two by sense.