Get familiar with the format, timing and content of the EOG subject exams that you have to take by visiting the North Carolina Testing Program website (see Resources below) and navigating to the grade and exam type that you're interested in preparing for. Check out the Information Sheet for each test to get an outline of what's covered and a sample of questions. Also pay attention to the time limit.
Speak with teachers in the subjects that you're taking the EOG exam in about preparing for the exam, handing out worksheets and exercises that help prepare for it and EOG-focused study groups.
Pick up an EOG Practice and Sample Workbook for each subject that you want to do well in from McGraw Hill-Glencoe publishers. Do as many practice questions as you can at the same pace as the test is given and then go back to score your practice exam. Look for patterned mistakes and identify weaknesses in your test taking habits.
Prepare correctly for the day of the test by going to bed on time and relaxing the night before the test. Do a quick review of the material but don't do any hardcore studying. Also, prepare a protein-rich breakfast and go easy on carbohydrates (like bread or pastries) since carbs are proven to make you drowsy during intensive concentration activity.