First of all, don't let this test intimidate you! It truly CAN be studied for. Although there aren't as many good books out there for this test as there are for some of the others, Priceton Review does make one. I scoured this book and wrote down every single text and name that it mentioned and familiarized myself with them. A great deal of this test is name recognition. You can pick up points by knowing the context of canonized texts and their authors, even if you've not read them.
I scored decently enough (600), but if I had it to do over again I would change two things. First, I'd simply spend more time studying. The problem is that this isn't the kind of in-depth study that we're accustomed to as literary scholars. It's more like a skim-the-surface-Cliffs-Notes kind of thing. Your time will be much better spent reading plot summaries than reading novels. This makes the test irrelevant, I think, since it doesn't so much test your critical abilities as it does the sheer number of texts with which you are familiar. But that's beside the point--we have to take it anyway, and it is what it is.
Secondly, I would give myself time to take it twice. I only had one shot at it, and I think I could have gotten a considerably higher score the second time around, after taking it once and having a better idea about how to study.
Overall, spend AS MUCH time studying as you can. Read the section introductions in the Norton to familarize yourself with historical contexts, and brush up on your literary terms. Think of the areas in which you haven't had much study, and become familiar with the "canonical" texts from those periods.
Most importantly, don't stress! It's important when taking a timed test like this to remain calm, because if you don't you won't be able to dig back into those corners of your brain that remember things like the differences between sonnet styles.
Best of luck!