Have everything you need to take the test when you walk into the test session:
The VEs are only required to tell you if you passed or failed. Some may offer more information but they cannot tell you about how you did on specific questions or topics.
If you wish to retake a failed test you must pay another examination fee.
Be sure to arrive ON TIME. The VE team can refuse to test you if you arrive after testing has begun.
The VE team may refuse to test you for any reason. An amateur license is a PRIVILEGE not a right. Generally only those who cheat or are disruptive to the testing process would be refused.
The Technician, General, and Amateur Extra exams are all multiple choice exams chosen from the "question pool" for that exam. The Technician and General exams are 35 questions each of which you must get 26 correct to pass. The Amateur Extra exam is 50 questions of which you must get 37 correct to pass the test.
Each of the questions has a "pool" of pre-defined questions that are selected at random for each of the actual test questions. The questions are presented in a random order and the answers are also randomized. You can't memorize that question T1A04 is answer C and expect to get it right. You have to know the actual answers. The best way to know the answers is to know the material - that is best done by studying.
The question pools are periodically changed and updated. The pools change on July 1st with the Technician pool last updated in 2014, the General pool updated in 2015, and the Amateur Extra pool updated in 2016.
I have found that the ARRL study books do the best job of not only teaching the questions and answers but also the actual material that goes with the questions and answers. You can just memorize the answers to the questions but you won't actually LEARN anything. If you want to progress to higher license classes you are much better off learning the material once.
Since this is a multiple choice test some simple tips for multiple choice tests are in order:
There are several places you can take sample exams on the web. They all use the standard published question pool but some do not randomize the questions and answers as is done on the real test. The ones I find best are: W8MHB - Practice Exams and Study Aids and AA9PW FCC Amateur Radio Practice Pages. These sites randomize the question order and the answer order just like the real test.