Are you caught in the hamster wheel of online market research, following your nose from one market listing to the other? Make sure you don't forget one of the best market research tools out there... the bookstore's magazine shelf. I hear tell that libraries have magazines, too. How about that?
Flipping through magazines first-hand helps you get a sense of what's made it into print, and you might encounter a few publications on the shelf that are new to you. After all, not everyone's guidelines are readily accessible online.
That's all well and good, but in my mind the best thing about thumbing through magazine after magazine is that I'm hit, rapid fire, with examples of other people's creativity. Seeing how others have fashioned a unique approach to seemingly mundane topics inspires me and gets my own creative juices flowing in a way that browsing online just cannot duplicate.
Don't forget to take a notebook along when you visit the magazine aisle - you'll need it to write down all the ideas you get once your brain is rolling.