With most eucalypt species new growth is extremely attractive to possums and successive browsing can kill them or the integrity of a tree's form can be destroyed.
By planting floppy, prickly bushes such as Derwent Wattle Acacia derwentiana, Spreading Wattle Acacia genistifolia, or Cape Pillar Sheoak Allocasuarina crassa for example may offer some protection from browsing by creating a difficult a barrier for possums to climb over.
Plant new plants in your garden at a time when the bush or surrounding area is not under stress from drought. This will minimise the risk of your garden plants being seen as an alternate food source.
Native plants obtained from some nurseries may have been grown using fertiliser which can make these plants more nutritious and hence more palatable to wildlife. Allowing them time to harden off before planting will reduce their nutritious quality. Alternatively you can protect them with chicken wire guards (plastic bags can sometimes get too hot).
Browsing of new plants by rabbits can be a problem. Rabbits are attracted to freshly dug soil. They are also attracted to roots and will even eat slow release fertiliser pellets. Rabbits do not like blood and bone, so this can be used as an alternative fertiliser. Placing rocks, leaf litter, logs or other objects such as pieces of wood or bricks around the base of plants until they are established will prevent damage by rabbits.
Rabbits can also damage well established plants, such as Allocasuarina species, South Esk Pine Callitris oblonga, Oyster Bay Pine C. rhomboidea and Silver Banksia Banksia marginata by ringbarking them. Keep an eye out for this happening - you may need to use temporary mesh or wire guards to protect the plants.
Most native plants respond to browsing by native animals but tip pruning by rabbits is different - there seems to be a herbicide in their saliva.

Illustration by Kris Schaffer