Well, you are on a wiki, so just go explore.
But if you want to make a little bit of an effort, you should of course start reading some of his books.
I’d recommend IT, which is one of his best. The best in my opinion. It’s also a brick of a book, so you could also start with one of his anthology books.
Perhaps you could start out with Everything's Eventual. That one has a nice range of different types of short stories, including one set in The Dark Tower universe which is Stephen Kings magnum opus and ties together much of his wiriting into a single universe. Or perhaps multiverse is a more correct term.
Once you’re hooked, you should give the dark tower series a try, but I think you should wait until you’ve read some of his other stand-alone stories first - including the stand -, because then you will get that unique feeling of how everything suddenly seems to be connected.
I don’t think I’ve ever found that sensation with any other writer. It’s almost horrifying in a very Stephen King sort of matter, when it happens ;-)
