I do actually think there's some merit to the idea of just "plunging in" - going ahead and attempting to read it! Sure, it will be a wtf experience in the beginning, but if you persist for a few hours, you'll start to build up a conceptual vocabulary used/established by W. of sorts (that's what happened to me anyway). But for many matters philosophy/intro-to-philosophy-X-related, I often find SEP to be an invaluable resource: http://plato.stanford.edu/search/searcher.py?query=wittgenst... - the articles there are quality stuff. Good luck with your rabbit hole :)

edit oh, and I had the pleasure of reading (only bits) from Ray Monk's bio of W. (http://books.google.co.uk/books/about/Ludwig_Wittgenstein.ht...), which is frequently referred to in SEP's article on W. (http://plato.stanford.edu/entries/wittgenstein/) - it might make for a very nice introductory exposition, if you're up for actually reading a (not-too-thin) book about him.