1. Familiar with algorithms and data structures: ACM topic mainly examines the application ability of algorithms and data structures. Therefore, we should first be familiar with commonly used algorithms and data structures, such as sorting, searching, graph theory, dynamic programming and so on. You can improve your algorithm level by brushing the topic website and participating in the algorithm competition.

2. Do more exercises: By doing a lot of exercises, you can improve your programming ability and problem-solving speed. You can choose some classic ACM problem sets to practice, such as Introduction to Algorithm Competition and Challenge Programming Competition. At the same time, you can also participate in some online programming competition platforms, such as LeetCode and Codeforces, for real-time programming practice.

3. Learn to analyze and solve problems: in the process of doing problems, learn to analyze the nature and characteristics of problems and find out the key points of problems. Then according to the characteristics of the problem, choose the appropriate algorithm and data structure to solve the problem. In the process of solving problems, we should pay attention to the control of time and space complexity and try our best to optimize the performance of the code.

4. Communicate and discuss with others: Communicate and discuss with other students preparing for ACM, and learn from each other. You can organize group discussions, solve problems together, or attend some training courses and lectures of algorithm competitions to learn and make progress with other students.

5. Keep practicing every day: ACM topics need long-term accumulation and training, so keep practicing every day. You can make a reasonable study plan and arrange a certain time for programming practice and algorithm learning every day. Only by practicing persistently can we improve our ability and level of solving problems.