In order to work in Australia, it is often mandatory (depending on the country you come from) to obtain a temporary visa of residence. It must be asked in your country of origin and it is necessary for you to be sponsored by a company of this same country. Your future employer will have to prove that no Australian corresponded to the profile that he was seeking, in order to justify your recruitment. He will have to publish two consecutive advertisements in the local newspaper. A procedure that always does not facilitate the employment from abroad and, very often, foreign people working in Australia are actually sent by a company. If you plan to leave to discover Australia, while working intermittently, ask Working Holiday Visa, you will be able to work 3 months with the same employer.
It is essential to require, as soon as your arrival, your Tax File Number (the equivalent of Social security number) at the Australian Taxation Office (Australian tax department). This number will be required when you start working.