Your question is too broad to be answered exactly. The only real common factor that groups people together as pagan is the belief in more then one god, and or that it is possible for more then one to exist.
Here's a little doodad from Llewllyn's book on "Witta", an Irish Pagan Tradition. The idea of dieties are part of a polarity, not a duality. This basically means that good, evil, and indifference are manifest in one central power. As opposed to being polytheistic, as many people would have you think, (neo) Paganism is pantheistic, meaning that there are many manifestations of one creative life force (A Christian may perceive this life force simply as "God") called by many names and worshiped in many ways.