Studying for the General Exam was more difficult to me than for the Technician Exam. For some reason I just couldn't seem to stay on task. What's so ironic is that I scored higher on my General Exam than I did on my Tech.
First things first beg, borrow, steal, or buy the book The ARRL General Class License Manual.
Note: The ARRL General Class License Manual is no longer published. The ARRL has a new book and it is available here.
There is quite a bit of theory here, I bugged the local guys to death with questions that I just didn't understand. They were always happy to help.
As with Element 2 you can download the Element 3 Question Pool. Study the questions and answers. Since I bought HAM University to practice CW, I used it and www.qrz.com while studying and pretesting. I would switch between the two to change things up a bit. I can't tell you how invaluable qrz.com is.
By the time you are ready to take your General Exam you should be passing your practice tests with at least an 80 four out of five times.
As with your CW test, you will need to bring a copy of your Amateur Radio License. You will also need to bring your CSCE from your CW exam. The VE's will need to send both of these in (don't worry, you'll get a CSCE with the passing of the General Exam).
OK, now you have tested and passed your General Exam. You can begin transmitting on your new frequencies but you must add '/AG' to the end of your callsign. Don't forget to check the FCC's website to get your updated license. Once the database is updated with your new privileges, you can drop the '/AG'.
OOPS!! I almost forgot. Now that you are using your new frequencies, make sure you are within the limits of your license. Check this Frequency Guide to be sure.