Plenty of good advice around, some dodgy advice too.
I would definitely be wary of PSS courses, or any other courses for that matter. Some may help, but some will very well hinder. Good photojournalism is good photography, and good photography is an art rather than a science. You can only learn so much in the classroom, but eventually you must do. And going through a course might lead to a false sense of not needing to go out and do.
Make no bones about it, photojournalism is not a well paying job in the grand scheme of things. Calling it a calling (sorry...) is probably a cliche, and probably not completely true either. That said, you can make a reasonable living from it. Based on Parchiao's checklist... I have landed property and a 1600cc car soon to be a European marque. I don't have a family but I don't think that's a money or job related issue. Okay, so I haven't done it in Singapore where it costs about 50x more to get landed property and a car, but if anything this only goes to show that it can be done, even if you need to be a bit more creative about how you do it.
Photojournalism is probably the one photographic line where a degree or other educational qualification could come in useful. However, the importance is not as much as you would imagine for other jobs. In photojournalism it tends to come as a bonus, rather than a requirement. I do have a number of friends who studied photography in some guise or the other (some of them only A levels for example) but they are not doing what they're doing because of their educational qualification. And I myself have absolutely no photographic qualifications.
Photojournalists work on different bases. Some are staff (such as myself), some work on shifts (as I have in the past), some work on spec (as I have in the past). I suspect the vast amount of Singapore work is staff based, although I believe Reuters and other such companies have stringers on shifts as well, although my knowledge of the situation in Singapore is fudgy.
It's Brian van der Beek, not van de Breek. He's a top lad, didn't know he was working for ST now. We don't know each other in person (although I have interacted with him online) but I've seen his early work, 'nuff respect.
Photojournalism doesn't have to be art, and therefore sacrifice. It can be a perfectly respectable 9 to 5 type of job (at least in terms of a regular decent salary), just not a regular high salary. If that's what you'd be alright with, then that's fine. Just don't expect to compare it to law, or David Beckham class salaries.
Tearsheets are useful, but you have to realise that in an open market, the guy after the job you're also after is also going to have tearsheets. Have them, but make sure they're good top quality stuff. The best pictures never get published (well, okay, some do, but many don't), so definitely don't just build your portfolio from work that is published.
I'd approach self-publishing extremely cautiously. The book market is exceedingly poor in Singapore. It's a big gamble to take, and if it comes off then you're laughing, but if, as chances are it will, fail, then you're left with a hole in a pocket that you're already in all likelihood struggling to fill.
Sex, prostitution and AIDS make juicy stories, yes. Other more routine subjects don't. But the bottom line is that in Singapore, the freelance photojournalist market is very poor, last I checked. SPH having a monopoly doesn't help, there's very little impetus for them to select better pictures than what they have already available to them. Paying for pictures is the exception rather than standard practice.
I disagree with Sadness' perceptions of fashion, sports and nature photographers. Actually, he didn't say very much, aside from fashion photographers earning good $$. The good $$ thing can be true, but not all the time. Photojournalistic based fashion snappers earn lousy money too. Good travelling? Hardly. Like *most* work related travel, it's not really travel. I should know.
On the topic of internship. Go assist a photographer *in the same field you want to work in*. Working with a good photojournalist is a completely different experience to working with a good commercial photographer. If anything, you don't learn anything directly from working photojournalists; you'll turn up with him/her, you'll both shoot, and then you'll go back and look and his work and feel stupid and see things you never saw at the time. But eventually that will rub off.
Does it need to be said that I agree with Ian's advice?
Your one unanswered question is whether you have a choice as to your area of photojournalism. In Singapore I would say it is very difficult. Over here the field is far more open, and there are dedicated news guys, dedicated sports guys, dedicated royals snappers, dedicated paparazzo. The lot. You can always aim high but be prepared to make compromises.