Most work in contemporary philosophy is done in epistemology. There is some work being done in ethics and political philosophy. Metaphysics doesn't garner a bunch of work anymore, as its major questions often can't go answered until epistemological ones are answered first.
As far as planning your reading, you want to start with introductions to philosophy, with special care to read about the Socratic dialogs. Socrates embodies, in his intuitive way of going about, what philosophers strive to be. From this, you can start down one of two routes first, metaphysics/epistemology, or ethics (you can do both at the same time too, but they each have slightly different paths).
Metaphysics/Epistemology: After this understanding the metaphysics of Plato and then Aristotle is a good idea. I would then mostly skip the medieval time period and head into modern philosophy: understand Descartes and his epistemology/metaphysics very fully (modern philosophy is based around Descartes), leading into Malebranche, Spinoza, and Leibniz. This group of philosophers were called the "rationalists." A small stop into the epistemology of Hobbes (he is mostly a political philosopher, but he has major contribution to epistemology as well) is then called for. After completing Hobbes, a dive into the "empiricists" is where you want to go: Locke, Berkeley, and then Hume in that order. Pay special attention to Hume, as he sets the entire stage for modern philosophy of science. Immanuel Kant comes next, and should also be given very special attention: knowing what a priori, a posteriori, analytic vs synthetic and a lot of Kant's ideas is vital to what is built on top of it. Kant is also widely regarded as the greatest philosopher to ever live. Study up on Hegel after Kant.
After Kant and Hegel you get into the more contemporary scene: understand the division between analytic and continental philosophy, and then laugh at the pitiful attempts of the continentals to do anything but pseudo-psychological babbling on about....
Sorry, I lost track there. Anyways, read Kierkegaard and Nietzche, but don't spend too much time on them. They have their ideas and they're important to understand, but they don't have all that much to say about epistemology. Your next real stop will be Frege and Russell, followed by understanding the Vienna Circle/Logical Positivism. Then you will hit the 20th century's biggest philosophy: Ludwig Wittgenstein. All of this should take you months, so I'll leave it off there.
Ethics: Luckily ethics isn't as broad, and to get a decent understanding of it, there are only a few key philosophers and ideas to really consider. First is Aristotle. Understanding Virtue Ethics is essential, as even today it is still alive and kicking. Next, study up on "divine command theory." There are really no exact philosophers associated with it, but it is a common theory. Psychological egoism and ethical egoism are important to understand. Utilitarianism: both rule utilitarianism and the classic utilitarianism are vital to understand Kant, and then Kant's categorical imperative is perhaps the greatest ethical thought in mankind's history. Really understand Kant and Aristotle...they're the two big names in ethics. Lastly, it's worthy to consider the ethical theories of Kierkegaard.