Sorry to disagree with everybody, but this isn't that clear-cut. "Fair use" doesn't actually cover quoting someone's work in your novel--it applies to reviews, academic discussions, and other non-fictional uses, not to embellishments of one's own fiction.
The fact that it is seldom enforced doesn't mean you're in the clear. Trust me on this. I and my publisher just paid 137 pounds for four lines from a WB Yeats poem (who knew his heirs were still collecting royalties?)
If quoted in passing--say, in an argument between two characters--you may be able to get away with it. Played with in the text in varius ways, you're probably safe. Quoted as a chapter head, less likely. Quoted as an epigraph to the book, less likely still. Discussing what someone wrote is fair use. Using what someone wrote to dress up your own work is pretty sketchy in "fair use" terms, and I think it should be obvious why.
Most novelists could only wish they were quoted and you probably won;t run into trouble there. Poets and their estates are stickier. Lyrics--well, within the text and just referenced or muddled or whatever, you're probably fine, but as quotes at chapter heads or epigraphs, unless the author is that famous fellow Traditional, you will pay. The music biz is rabid on this point.
Nonetheless, the time to worry is not until the publisher raises the problem. Write first, worry later.
