I recently passed the NCLEX-RN, which for most individuals is a very scary, intimidating exam ... and in fact it is! However, your confidence will improve the more questions you do. That's really all there is to it. Studying content alone like you do to prepare for nursing school exams is not effective for this exam. The simple reason for this is that the NCLEX-RN is a computer adaptive test, which means that questions are provided to you based on how you answer previous questions. With thousands of questions in the NCLEX-RN database, every candidate will have a very unique exam from the next candidate. Some may have several pediatric questions while others have none, etc. It's all about answering the questions smartly. The content you learned in nursing school is enough knowledge you need to pass the NCLEX-RN, you just need to develop endurance and confidence with question structure, and the only way to do that is to consistently do questions and review rationales for the questions you get wrong.
If you are interested in having me tutor you in NCLEX-RN preparation, feel free to send me an inquiry. Thank you!