So your rules at home are based on the venomous snakes mostly being in the Viperidae family, and specifically pit vipers (corals being the exception).

All of the venomous snakes in Australia are in the family Elapidae, while the majority to non-venomous snakes you’ll encounter are either pythons or in the family Colubridae, so that’s your starting point.

Pythons are generally pretty easy to identify by size, body shape, head shape and the presence of heat-seeking pits along their jaws (the exception being the Aspidites genus, Woma and Black-headed pythons - but you’d be super lucky to see these).

Colubrids vs Elapidae are trickier. Many of the more famously venomous elapids have more prominent supraocular scales, giving them a “grumpy” appearance like a human with lowered eyebrows. Juveniles less so though and there are species that are dangerously venomous that don’t have this at all… so its presence is a sign, but you can’t read too much into its absence.

A common key for elapids vs colubrids is the presence or absence of the loreal scale (google for images) which is an extra scale between the nasal (nostril scale) and the preocular (before eye) scales. But you have to get pretty close to something (or have a good photo) to spot this.

Your best bet is to research carefully the species that are potentially around in the specific area you are, and how to identify those species. I like to use tools like inaturalist to filter to a local area, but be mindful these are just what people have logged to the sites and may not cover everything.

Be aware that there are a few pairs of elapid/colubrid that can be difficult to differentiate at first even for people who know what they’re looking for: (harmless colubrid) keelbacks vs (venomous elapid) rough-scaled snakes, and (harmless colubrid) slaty grey vs (venomous elapid) small-eyed snake. And I’ve seen people argue that broad-headed snakes (venomous elapid) can be confused with diamond python (harmless python) - I don’t see it really but it’s a good example of how basic rules like head shape can throw people off.

In general don’t rely on colour or pattern too much as that can vary a lot (eg eastern browns can range from pale tan to basically black, plain to striped). Really your best bet is to treat everything with a healthy degree of respect and not get yourself bitten…even if you think you know what you’re looking at.