Part of the problem is also mainly due to the glut of freelancers around. Whenever there's an assignment up for grabs, there will be so many people eyeing the same one. Because there are so many freelancers, usually companies are unwilling to pay a premium price for your services especially if you are untested; they will be taking a risk in hiring you. Even having a portfolio doesn't help anymore since they know lotsa pictures can be achieved thru repetitive photo-taking.
My advice is not to expect too much when you are seeking a photo assignment. You may be full of confidence with your own skills, but the important thing is your potential clients are not. Be willing to work for less the first few times, and if you really show promising results, they will be more willing to pay if you ask for a higher price next time. So far, this method has never failed me before and has the clients coming back to me more often, which is really the important part.
If you just seeking one-off large payments, I'm afraid you wun go very far, especially in Singapore.