Read.
There's not much point just learning new words. I mean, how often do you get to throw words like sesquipedalian or tintinnabulation into a conversation?
Reading allows you to expand your vocabulary at a rate that's comfortable, and you will learn the words and their usage in context. Once you start to build your vocabulary select tougher books and they will help you to build it even further, as well as adding to your personal information data bank.
