If you were interested in Foucault, I'd actually suggest "Power/Knowledge" (a collection of essays) or Rabinow's "Foucault Reader" before diving into something like D+P ... better to get a solid background first, IMO.
It's hard to recommend a specific philosophy book unless you really specify what area of philosophy you're interested in. Naming some general area (even something as broad as analytic or continental philosophy) would help.
And for the love of god, don't read Ayn Rand.
If you've never done any type of philosophy reading before and just want somewhere to start, I'd start with one of the following authors:
-Plato (Euthyphro, Crito, the Apology, Symposium, etc - all easy to read and good general introductions to philosophic thought)
-Nietszsche (The Gay Science, Groundwork for the Geneology of Morals, Beyond Good and Evil - a good starting point for most modern philosophy, especially if you're interested in reading Heidegger, Sartre, Foucault, or others eventually)
-Wittgenstein (Tractatus, Philosophical Investigations - might not be the best place to start, but if you're into analytic philosophy this would be very interesting)