If your experience in reading Slavoj Žižek mirrors mine at all, most likely you started out by reading one or two of his more ‘famous’ works (e.g. Puppet and the Dwarf, Parallax View, Ticklish Subjects, etc.) after which you found yourself asking what the hell you just read. Žižek’s writing is by nature asymptotic i.e. attentive readers always almost get what he’s saying but the ideas, alas, tend to elude our grasp in the final analysis.
It doesn’t help that in his books Žižek’s ideas are all over the place and students end up having to ‘map out’ his ideas according to themes (what I had to do for a entire year when I was studying him) and even then readers easily forget what the key points were, let alone the qualifications.
We never, of course, forget the jokes. Hence, one tip (in addition to the below) is to map the relevant themes according to some of his most popular jokes (e.g. what area of Lacan’s thought does the wheel-barrow joke cover? Or the one involving the man who thought he was a worm?).
Anyway, this is one quick recommendation to help you understand Žižek better: Read his responses to critics.
This is (probably?) the only way to ‘lock him down’ systematically, forcing him to reply to specific objections, clarify specific points and so on.
Hence, IMO, an invaluable work for understanding Žižek’s basic ideas is Contingency, Hegemony & Universality (Verso, 2000), the book Žižek co-authored with Judith Butler and Ernesto Laclau. The payload is the second and third chapter penned by Žižek in response to the other two. I suspect that if this book hadn’t been written, I still wouldn’t have ‘gotten’ the meaning of the gaze, of the traumatic as thematic, etc.
Another great book is Glyn Daly’s Conversations With Žižek (Polity, 2003), which had the added benefit of including some biographical material (e.g. about how he stole letter-heads from other universities to forge acceptance letters, etc.).
You can also find some helpful clarifications in In Defense of Lost Causes (Verso, 2008) where he responds to Yannis Stavrakakis during which he distinguishes between enacting the the loss object and enacting loss itself; Organs Without Bodies (Routledge, 2004) is great if you’re a fan of Deleuze; and not forgetting his exchange with John Milbank in Monstrosity of Christ (MIT, 2009). The overall point is each time you read Žižek try to zoom in on those passages where he’s writing specifically to refute another thinker.
(One exception to this ‘method’ is his fiery exchanges with Simon Critchley and Noam Chomsky which, IMO, confuses things even more).
There are also at least two books devoted to explicating and criticising his works — The Truth of Žižek (Bloomsbury, 2007) and Traversing the Fantasy (Ashgate, 2006) — after which Žižek supplies the closing chapter.