I think you will enjoy Inherent Vice. It's nice and juicy, so take your time. It's not a race to get to the end of the book, and this one is one to think about as you read.
As with any book or poem that is considered "real" literature, I always recommend doing a little pre-reading. Google Pynchon and read a criticism or two about the book, the writer, and the times in which he was working. No need to make an extensive study, just sort of familiarize yourself with the general ideas you will be presented with.
We used to have to go to the library and find books or journals with a discussion of the material. Now it is soooo easy to just go online and find tons of info. Take advantage of those criticisms and it will really enrich your reading.
But just briefly. Don't over-prepare and ruin the experience. And enjoy the book!