Hi there
When we moved over, we dealt with a lady called Patricia, who works for SingaporeExpats \. She had to jump through a few hoops, since we had a very short amount of time to find a place, and she was completely professional, unlike the three we had gone through in quick succession before her. The rule of thumb here is find one agent and stick to them.
Fill in the web form on their website (look for the contact us link at singaporeexpats dot com)and they get back to you in no time at all, verifying details and getting an agent to you. Just tell them what requirements you have, they do the rest. Good luck!