Also 4x4 WA is a great show to see local tracks and stuff & u can watch it online.
(4x4 Western Australia - Welcome) check out the 2nd or 3rd episode on MOA, looks pretty sick.
If ur looking for close to perth itself there are the powerlines at Mundaring (look up Flynn rd on google earth & go from there). Or the pines off Gnangara rd near ellenbrook & lexia.
For sand u can do wedge to the north and around lancelin (big dunes). Depends how far afield u want to go really.