Reading in general will increase your intelligence, but probably the best advice I can give you is to just be curious.
Read everything you can get your hands on. I prefer to read fiction, but right now I'm on a non-fiction kick with a bit of history. If the book is boring, I throw it away; I'm not going to be alive for very long, lol.
Reading will increase your vocabulary, even more so if you actually pay attention to the words used and take the time to look them up. Read classics, like Alexander Dumas (Count of Monte Cristo, Penguin edition, unabridged trans. by Robin Buss), Rafael Sabatini (Captain Blood), Henry Fielding's Tom Jones, Dostoyevsky's The Idiot and Crime & Punishment, Dickens (never read him), Poe's The Cask of Amontillado, etc etc.
For example, the word "pusillanimous" can be found in Preston & Child's RipTide. "Machicolation" is in their Cemetery Dance. I learned "bathyscaphe" and "intransigence" in Alistair MacLean's books. "Sedulously" was in On the Beach. So on and so forth. I also keep a list of words in the drafts folder of my Gmail account that I can easily add to. (I like words.)
I keep sticky notes in my wallet and a pen in my pocket. If I think of / see / discuss something/anything that I'm curious about it, I'll write it down. I'll look it up later online. I do this all the time when watching movies.
I actually don't have a very good short term memory, so I find myself looking things up repeatedly sometimes, but I love looking things up. There should be a word for it. Probably not-quite-erudite. How about that?