Setting up Mac OS X on a PC can be an extremely tricky process-- since Apple never intended for the operating system to run on any third-party hardware, Mac OS X can suffer from all sorts of bugs and hangups when you try to start it on your own PC for the first time. If your Hackintosh can't properly boot for some reason, then you'll probably have to turn on OS X's "verbose mode" to diagnose the problem. Verbose mode transforms the standard gray Apple boot screen into a text-based interface, from which Mac OS X will print out every single process that it runs in the background as it starts up. This way, you can tell exactly which process is messing up the startup process as a whole.
However, using verbose mode itself can be very tricky. After all, Mac OS X has to run hundreds of different processes at once to start up properly, so interpreting your results from verbose mode is often extremely complicated. This guide is here to help.