Which platform to use if I am looking to invest in S-Reits for first time investor?

Hi TX, instead of purchasing specific Reits, you may also wish to consider purchase a Reit ETF to ease your selection process as well. Seedly has also done up an informative article that you could check out: https://blog.seedly.sg/singapore-reit-etfs-guide

As for the platforms to use, you should choose a brokerage that minimises the costs in performing this trade. Here are some comparison which could be helpful for you: https://seedly.sg/reviews/online-brokerages

You can look at SYFE on their REITs portfolo...they are robo advisors and as a first time investor, i suggest try robo advisor first...