choices:
1) marry an Australian girl. then apply.
2) sell off all your assets and apply via the investor/ set up a
business scheme with a minimum capital. then apply.
3) go there study higher/ advanced degree. then apply.
4) go there find work with the sponsorship of an australian
company/ employer for a senior executive/ managerial position. then
apply with employer's support/ endorsement.
from:
http://www.singapore.embassy.gov.au/sing/Visas_and_Migration.html
http://www.immi.gov.au/
1) Did that but got PR first. 
2) That'll take quite a few quid.
3) Did that. Worked like a charm.
4) Don't waste your time unless you're pretty damn special -
I've lost count of the number of job applicants I've turned down
because the paperwork's a nightmare.
The easiest route is skilled migration, which works on a points
system based upon things like edcucation and occupation. Even
so, time's of the essence - every five years loses you one
point. Also, whatever qualifications you hold need to match
Australian standards - if you have a Singaporean qualification and
experience, it needs to be vetted by an Australian industry
body. If you have an Australian qualification, it will be
automatically recognised for the first six months after it is
earned - after six months it is considered out of data and will
need to be re-certified.