Hey,
This is my first year in an AP history class, and the first test I took I bombed. I studied for hours but still didn't do very well. Do you guys have any tips to help me with these difficult tests?

One tip that really helped me out was to memorize the presidents in order and the years in which they served - I would just look at the ones from the sections we were studying so that it wasn't too long of a list. If you can remember the presidents and some of the major events and/or characteristics of their term of service, it's much easier to draw contexts for questions and put you in the right historical frame of mind.

Other than that, just reread the notes and keep an eye out for major names and dates; it sucks, but it's the only thing that's pretty much guaranteed to help.

make sure you know exactly how the exam will work:

www.apexamreview.com

You might want to print out the notes from here and use them for review...

Otherwise, as an AP US teacher, I recommend using part "F" in your Guidebook (Am Pag)--Cause and Effect. If you can't do those without looking, you don't know the chapter well enough for a test. Make sure you know the vocabulary from the first page of each Guidebook chapter, as well as Part C identification.
The questions at the end of each Guidebook chapter are also useful. You should be able to answer all of them, with examples to back up your assertions.