AP European History
Again, just like Art History, unless you are amazing at memorizing dates and names, don't try to self study Euro. Granted, it is not as hard as Art History, but it is still heavy on the memorization. The key thing that you need to know is trends. You need to be able to understand what happened and why. It's not so much about exact days and names, but about a general idea of history and how it panned out. You should also know days and times, because those will most definitely help you.
As far as preparation goes, I would recommend the Princeton Review AP European History book; it gives you a thorough idea of what is going on along with side notes on what is important for the AP test. I also used the REA AP European History Crash Course Book for right before the test. It gives you a good idea of what you need to know in the order to do well.
Note, I also used the Five Steps to a Five AP European History review book, but I felt like it focused to much on specific events and less on the themes and trends you need to understand to do well. However, I really liked how it wasn't as casual and "friendly" as the Princeton Review book. Princeton Review is often too casual and doesn't seem like a serious study-aid. However, if you have difficulty paying attention to review books, it can be easier to read something that is a little more friendly and casual.
I've also heard that using SparkNotes is very helpful! I've used it from many other tests, but not Euro. It tells you what you need to work on and the most important stuff.