A History of Western Thought: From Ancient Greece to the Twentieth Century

This is also my experience with reading philosophy; just like significant works in any other fields, you can't approach many important books of philosophy head-on. You have to first get an understanding of the bckground, which also allows you to understand the fundamental dichotomies, and why different philosophers treat different questions as the primary ones. In this respect, the best history of philosophy I know of is Skirbekk's "A History of Western Thought: From Ancient Greece to the Twentieth Century", a highly recommended read.