You can check the exam subjects of the Party History major online, look at the subjects in recent years, and determine the most basic review direction. Secondly, it's best to find a graduate student and give you some guidance.
Make it clear that the Central Party School is very difficult, not only to pass specialized courses, but also to be strict with English. The difficulty of specialized courses in Party schools can basically reach the level of graduate students and even researchers in general universities. At that time, a classmate in our class took an exam and passed a doctor's degree from the Central Party School, which was naturally awesome. He did intimate counseling for more than a year before he was admitted, hehe.
The central party school, the gatekeeper, is a retired cadre of the CPC. The operator of the library is at the official level, hehe, the communication gap is too big and it is difficult.
But there is still hope, hehe, I wish you success!