Trees on your property can improve land values, provide environmental benefits and potentially provide some level of commercial income.
There is a lot of information around on tree planting and a lot of interest from the Australian Government in promoting tree growing to sequester carbon.
However, there is so much information around that it can be difficult to see the trees from the forest - pardon the reverse pun!
So before you do anything I suggest that you read this publication [1] on selecting tree varieties for small holdings (even if you are a farmer). This will help you clarify why you want to grow trees and help you plan the next steps.
Once you have read this then browse the libraries that we have on the farm forestry [2] and biodiversity options. These have heaps of resources to help you plan and implement the next steps.
Links:
[1] http://www.agric.wa.gov.au/PC_95003.html
[2] http://sustainableagriculture.perthregionnrm.com/library/pastures-fodder-and-tree-crops/farm-forestry