Perth or Melbourne

I'm currently planning my working holiday in Australia

When will you arrive here? Do you basically want to explore the whole country during your 12/24 months in the country?

When will you arrive here?

end july - mid august

Do you basically want to explore the whole country during your 12/24 months in the country?

I would like to but it has to get funded (not 100% but I don't want to blow all my savings on this)

Do you have the opportunity to fly into any one of Darwin, Cairns, Brisbane, or the Gold Coast?

Perth, Adelaide,Melbourne, and to some extent Sydney, are mostly cold and wet (or at best, cool and weakly sunny).

Head to the tropics indeed ... until about late October, it's the best place to be by far. As for your original question, Melbourne is thousands of times more interesting than Perth. And the mining province jobs in WA have finished.

You probably want to consider a few things, first being that the reality of getting work in the mining industry is likely a minimal chance though the possibility may exist to get lucky with a cleaning/services type of contractor.
That said, there will be far more working opportunities on the east coast and if you are arriving in July/August, I would say you ought to consider arriving in Brisbane if you want work to start off with and that is a sound approach.
Best opportunities would exist in the coastal/inland stretch between Sunshine Coast and Cairns regions.
Have a look at https://jobsearch.gov.au/job/search/harvest and as for dangerous jellyfish, just beware of the danger, particularly in more northern Queensland from about October on as well as Crocs all year around and if in doubt ask a local.
From about October/November, it will start to get warmer and more humid in the far north as the wet seaon develops and so at some stage you may want to reverse your travel and head south and you will start to see more seasonal opportunities in southern states but again consult the harvest trail.
As summer weather starts to finish in the south, you could again head north for some travelling, April through to September being good for generally having better weather in the tropical regions.

Here is a broad twelve-month program guide:

August: Darwin
September: Kimberley
October: Pilbara / Perth
November: Adelaide / Melbourne
December: Sydney
January: Sydney
February:: NSW North Coast
March: Gold Coast
April: Sunshine Coast
May: Central Queensland
June: Whitsundays
July: Cairns / Port Douglas

That gives you a guide to a perfect year in the country.

You mention this being your first trip and not knowing what is most important and here are a couple of key points in travelling, first the money angle for unless you have an endless supply of it, money does get consumed at a rate you may never have imagined, so without an endless supply you need to have something of a budget and do some planning that will stretch what funds you have and to add to them as you go, hence the harvest trail; some people also able to find other work depending on their skills, sex and luck, for instance girls will be more likely to pick up nannying work and even waitressing/bar work more so than guys, but for whatever work you manage to get, there is always going to be an element of luck in being at the right place at the right time.
You ought to visit a few different hostels wherever you are staying for most will have noticeboards with work opportunity advertisements, a lot being sales orientated and something to be wary off but also talking with as many travellers as you can about work is also another way of learning about opportunities.

What coalcliff may have attempted to put forward in being perfect would seem to be based on weather just for following warmer weather and that will not necessarily mean finding jobs.

The second point in travelling is what interests do you have and that can also affect your travel pattern, for if you wanted to have something of a snow fields experience, you would want to hang around a bit in the south during winter./early spring or at least revisit that region if it was experiencing a good snow season, so what is perfect if there is ever one is in the mind of one seeking it.

What Coalclifff may have attempted to put forward in being perfect would seem to be based on weather just for following warmer weather and that will not necessarily mean finding jobs.

Yes ...I am talking primarily about weather, and the best/peak times to be in various regions ... it's a large continent with diverse climate, so it needs to be considered ... it's a key factor in having a great year.

And indeed a lot of work does follow the seasons pretty well ... you're not going to find Barrier reef resort work in December, for instance.

Big cities tend to be constant year-round, and if you do decide to do rural work to secure a second WHV year, then it follows its own pattern depending on the region.

Worrying that you believe there is nothing closer to Perth than at least 1000km, the belief the people of Perth &The West are some what narrow minded, that all people along the east coast are homogeneous, your needs can only be fulfilled by being in a centre of city surrounded by kms of urban sprawl.

Depending on what role you expect to get in mining, if it is construction you may want to focus in infrastructure builds such as the Canberra or Newcastle Light Rails programmes.

Worrying that you believe there is nothing closer to Perth than at least 1000km, the belief the people of Perth &The West are some what narrow minded,

Having lived in Perth for two long years ... both of these are definitely the case!