Any information regarding working, studying and migration to Australia are of the exclusive responsibility of Australian authorities. Therefore, please contact the Australian Department of Immigration and Border Protection.
On their webiste, there is plenty of information regarding visas to Australia.
The Australian Embassy in Lisbon does not grant any visas or information regarding this matter: www.portugal.embassy.gov.au
All questions regarding visas to Australia must be forwarded to the Europe Service Centre in London (+44 20 7420 3690).
This service is open Monday to Friday, from 9.00 to 16.00 (CET), with the exception of some British and Australian public holidays).
You can also send an inquiry to the Europe Service Centre at www.immi.gov.au/contacts/forms/europe.
If you wish to speak with a Portuguese official, you can contact the Americas Service Centre (+1 613 236 7603), Monday to Friday from 15h00 to 22h00 (CET) or send an inquiry via www.immi.gov.au/contacts/forms/americas.
Regarding an eventual use of a migration agent, read the immigration website beforehand, which states:
“If you choose to use a migration agent, you should use a registered migration agent. In Australia, agents must be registered with the Office of the Migration Agents Registration Authority (MARA): https://www.mara.gov.au/.
Information about easily finding registered agents and the dangers of using unregistered agents is available. See: Don't Get Caught Out by Unregistered Agents”.
Information on working in Australia: TrabalharEstrangeiro_brochura2015
Information for qualified workers and businesses: