How do I keep sweat out of my eyes?
When wearing a helmet (and you're in Australia, so I assume you are) I almost always use an undercap, be it a classic styled cycling casquette, a skull cap or, in winter, a thicker beanie, perhaps with ear protection. 

In summer a casquette works well because I find that the sweat does form on the peak, but can then either drip off or evaporate more easily.