One of my Australian friends once told me something, which I've never forgotten. In most countries, English is spoken reasonably clearly. People often pronounce words clearly, in a way that is easy to listen to. However there are some accents which are the opposite - and the Australian accent is a great example. This means that the Australian accent can be difficult to understand - the words are much less clear (on average) compared to more formal accents. Public speeches will be different - politicians (for example) will tend to put more emphasis on clearly pronouncing words (rather than slurring them together).
It is very difficult to communicate what I'm trying to say in writing, it's easier to explain vocally... but I will try. In the USA or UK people might ask "how are you today?" but in Australia the pronunciation is more like "heeeyaoow yaa go-arn maaayyytttt", but with a very lazy tounge/mouth/voice. Some people often try to imitate an Aussie accent by repeating the words Australians say, but that doesn't work very well. A better way to imitate an Australian accent would be to copy the words, copy the sounds, and then try to move your mouth as little as possible, and make the words blur together in the laziest way possible! For example if I say "how ya going mate" out loud, the only time I need to move my mouth is to say the "m" of "mate"; the word "going" becomes "go-arn", etc.