Australian plants need only a little fertiliser, and the slow release type is recommended. Over-fertilising is counterproductive because, just like over-watering, it produces lush growth that attracts pests and diseases.
Kangaroo paws are particularly susceptible if you over-feed them. For genera that cannot tolerate phosphorus, use a fertiliser that has been specially formulated to their needs. General fertilisers containing phosphate can be used on genera that are able to tolerate phosphorus, allowing you to grow them in combination with exotics.
Read the label to see whether it recommends a dosage suitable for 'native' plants, and always use a measuring cup rather than just throwing on by the handful.