From experience last year, there were 3 parts in total : written test (in both Chinese and English), 1-on-1 client meeting exercise and group discussion. 

My little tips would be: 

1. Written test : be familiar with the background and current development of HASE. Also the trend of HK banking industry. 

2. 1-on-1 client meeting exercise : more focus on soft skills (communication, social, people skills...). You have to answer enquiries from the client regarding some banking services and products. Get ready to be challenged by him/her. Don’t have to be afraid when challenged, it is a part of the test (stress testing). 

3. Group discussion: 10+ pages of reading materials . Show your collaboration and communication skills. Do not dominate the discussion but actively give your opinion and suggest extra idea.