When planting your garden consider planting local native bushes and trees. It’s better to choose local plants rather than plants native to another part of Australia as the local plants will extend rather than overrun our bush areas. The animals and birds appreciate local plants the most. A garden nursery should be able to help you. This 
Indigenous Plant Species List suggests local plants for certain soil, sun and height conditions.
Nestboxes are another interesting and essential way to make your backyard are haven. Possums, micro-bats, gliders and hollow-nesting birds need these shelters to breed, and most trees with naturally-occurring hollows have been removed. Remember, put them up high and away from your home to limit noise at night. You can get some detailed information in 
Nestboxes for Natives.
Bush-friendly backyards provide shelter to animals and birds trying to move from one patch of bushland to another. They don’t spread weeds, and they increase biodiversity. To get more information apart from what’s listed below, read the 
Bush Friendly Neighbour Brochure, and look at the Bush Friendly Neighbour Poster.
Before you start… observe! If you have a messy overgrown corner that may be the best spot you have for animals! Watch for about a year before you make any major changes to see who you will be disrupting.
Be smarter than your weeds and know their weak spots. It will be easier for you to remove them if you attack when they are the most susceptible. Compost your weeds under black plastic to stop the seeds blowing around.
Where possible provide a range of habitats including canopy plants, mid-story and groundcover vegetation layers. Clumps of dense shrub are good, and you can plant trees to create aerial corridors.
Planting non-nectar, insect pollinated plants like wattle, native peas and tea-tree to encourage smaller insect-eating birds. If territorial birds like currawongs or noisy miners are a problem, reduce the number of plants that bear fruit and have heavy nectar (like hybrid grevilleas). Clear and constant water also attract birds.