Hi there! Firstly, you need to know your desired coverage basically which type of insurance you want as there are a few types of them. Next, you need to understand the policy excess as some insurance might offer to waive the access. Additionally you need to consider insurance that offers coverage across the causeway, courtesy or replacement car, and no-claim discount and premium rebates.
To find out more, you can check out this article: https://www.motorist.sg/article/167/5-things-to-consider-before-buying-car-insurance-in-singapore