/lit/ - Literature

I'm just getting into Buddhism and currently reading "What the Buddha taught" but I'm having trouble reconciling the fact that there are so many Buddhist traditions with belief in different kind of esoteric practices, particularly tibetan Buddhism. How is it that one can "navigate" spiritual/esoteric realms if there is no "soul" to experience them? Or how is it that one can influence the conditions of their next rebirth through karma if there is nothing that "accounts" for the karma at the moment of rebirth?