I was very intimidated by what I'd read online about the exam, but I found it to be easier than I expected.

The Rita Mulcahy book was key for me.  I read it three times, which took months because I'm a working mom.  I took many free online exams (don't forget to make sure they're based on the current edition of the PMBOK!), and those helped me identify gaps in my knowledge, but they also made me nervous.  My actual exam didn't include any obscure terms or concepts like some of the online versions did.