Belief is all-important.  If you wish to connect with a loved one who has passed or your unseen helpers across the veil, belief will open the door.  This is not to say that you will not have spontaneous anomalous experiences, such as a ghostly visitor standing at the foot of your bed, but if you do not believe it is possible for you to see or hear or communicate with spirit, then your thoughts will create that non-possibility.  There are other factors which go into spirit communication, such as raising your personal vibration, but start with the belief that it is possible and you are well on your way.