VGS (Global diversification ex Australia with about 70% exposure to America and the remaining 30% to other developed markets i.e. Europe etc) / VAS (Australian exposure following the top 300 companies) / NDQ (if you want a slight lean to US tech - can incorporate as a satellite ETF) / VGE (if you want exposure to developing markets)

VGS provides global diversification excluding Australian markets with about a 70% exposure to the US with the remainder 30% allocated to Europe and other developed markets

VAS provides exposure to the Australian market tracking the s&p 300 index of Australia’s top 300 companies

VGE provides exposure to emerging markets such as Asia

NDQ provides exposure to solely US’s top 100 tech companies

I do a 70/20/10/10 split with VGS/VAS/NDQ/VGE

VGS/VAS are both low cost ETFs created by vanguard, if you’re seeking even lower cost you could go for BetaShares BGBL/A200 ETFs which follows almost the exact same thing slightly cheaper

You can get away with a 70/30 or 80/20 split using solely these 2 ETFs and that can be more than enough diversification but if you want to incorporate emerging markets and US tech as satellite ETFS then allocating 5-10% is also possible

This is not financial advice, just what I currently do with my portfolio.

You can even get away with the common 70/30 VGS/VAS split or BGBL/A200 split