One of the basic texts in semiotics is Mythologies by Roland Barthes. It's a very nice text because it's mostly composed of newspaper articles, which are then followed by a moderately dense 30-page essay. Very readable for the beginner in lit. theory. He's drawing a bit on Ferdinand Saussure, but he does a good job of recapping Saussure in there, so I think you can probably follow him without reading Saussure separately first. If you *want* to start with the Saussure, you want to look for a book called Course in General Linguistics, and then read the following section:
"The Object of Linguistics" (pgs. 141-168)
That's pretty much the core of beginning semiotic theory.
Once you've tackled those, you can either continue on through semiotics, structuralism, and post-structuralism...or, if you're more interested in the post-colonialist stuff, take a detour over there. For that, you want to read Edward Said, but since Said (pronounced Sayeed) was a student of Michel Foucault, you should probably start with Foucault. Who is just fun anyway.
You can really pick up anything of Foucault's -- what he does is develop a theory about how aspects of society evolve, and then he applies it (with more or less success) to different things. So if you're interested in seuxality, pick up his History of Sexuality, vol. 1. If you're interested in crime, pick up his prison book, Discipline and Punish: The Birth of the Prison (which I love -- great gory torture scenes at the beginning). I haven't read Madness and Civilization: A History of Insanity in the Age of Reason, but I hear it's also quite good. He's *very* readable -- lots of entertaining examples.
Once you've done some Foucault, go get Edward Said's Orientalism, which basically applies a Foucauldian interpretation to the way academics (and others) thought about the Orient. You'll end up saying 'hegemony' a lot by the end of it, and enjoying it. :-) Also very readable, and generally right, I think, even if he gets some small things wrong.
Of course, once you start reading Barthes, you could just get stuck on him, 'cause he's so fabulous. In which case, I'd try Camera Lucida next; a really interesting book that's part an essay on photography, and part a memoir about his mother. And part semiotics, of course.