One of the first lessons neophite PR professionals (should) learn is to know a journalist and what they cover before you pitch. That’s sometimes easier said than done.
But I have found that Twitter can be an invaluable tool for researching a journalist. Apart from hiring a mind reader (unrealistic) or stalking (illegal), there’s really no other way to listen in on the conversations, thoughts and opinions of a specific journalist. If you’re trying to get on the radar screen of a reporter, follow them on Twitter and pay close attention to what they’re tweeting. It’s a wealth of information.