That's a tough start, why not start with some secondary material to give you an overview, like:
http://plato.stanford.edu/entries/metaphysics/
I especially like the final paragraph of that article:
"The weak form of the thesis that metaphysics is impossible is this: there is something about the human mind ... that unfits it for reaching metaphysical conclusions in any reliable way. This idea is at least as old as Kant, but a version of it that is much more modest than Kant's (and much easier to understand) has recently been carefully presented in McGinn (1993)."
McGinn's argument is that the human mind is incapable of a satisfactory treatment of a large range of philosophical questions, a range that includes all metaphysical questions. I've read a couple of McGinn's books and think he is a great philosopher, in fact, he's the best contemporary philosopher I've read, and he's not difficult to read.
So in embarking on this journey you should remember that the greatest philosopher of modern times (Kant) thinks no one is up to the task of doing any sensible work in metaphysics, and gives very good arguments as to why this is the case. Almost all decent, contemporary philosophers agree with Kant (that's why Kant is thought the greatest!)
So, if I was you, I'd start by reading McGinn, and if you are still tempted to explore metaphysics, try Kant's first critique, that is, "The Critique of Pure Reason". This is a very difficult work; I like Pluhar's straightforward translation, and found Caygill's "A Kant Dictionary" invaluable.
Doing all this (tough!) reading in metaphysics, or more precisely anti-metaphysics, has made me immune to believing in metaphysical nonsense, like: the Christian God, enlightenment, nirvana, rebirth, Brahman, Atman, eternal soul, angels, Plato's forms, "Aristotelian unmoved mover", Hegel world spirit, Nietzsche eternal return, Stoic Zeus, Spinoza pantheistic God, ontological arguments, Descartes God, any other Gods.
Kant & McGinn are great garbage removal men, they have cleaned out my mental space, for that I am very grateful
