It depends what you mean by IQ. Intelligent Quotient is the abililty to do intelligence tests! If this is what you want, buy or borrow a book of intelliegence tests and do them. When you find some you can't do, or do but get wrong, then look up the answers in the back of the book and work out how they were achieved. That way, you'll learn how to think in the same way as people who write intelligence tests.
If you just want to become more knowledgible, then read a "good" newspaper from cover to cover every day. You'll soon accumulate a whole load of info.