Some general tips for snake prevention:
Keep all grasses low.
Keep gardens simple and avoid close root, ground hugging plants like agapanthus and ivy (these make great protection for snakes from natural predators as they can camouflage very well in the tight leaf and root structure, they also provide hiding places for snake's food items such as frogs and skinks)
Keep wood piles away from the house and elevate off the ground where possible, wood piles kept in secured sheds are most ideal, i.e.; garden sheds without any holes and a concrete floor.
Reduce rubbish in the back yard, if it is necessary to have sheets of corrugated iron and colourbond in your yard, separate with bricks and elevate off the ground, alternatively don't lay flat on the ground.
When building rock walls, stop up any gaps with mortar, any hole could be a potential snake hide.
Stop up any gaps in fence lines with snake and mouse mesh (5mm gauge mesh available from leading hardware stores), dug in at least 5cm. Alternatively build a colourbond fence and have it dug in at least 5cm, with no gaps along the edge.
Keep composts in bins, without any gaps for rodents to get into.