I want acreage but I also want an investment property

We have Just finished up travelling Australia for the last 2 years. We have approximately 3/4 of a mil in cash assets with no debt. We have secured a rental for the time being until we figure out the next steps we want to take in life. There is one certainty, we want a property. We know we want acreage (which we can get for approx 300k) and build our dream home (no idea on price), but also I wouldn't mind an investment property to rent out.

So, if an expert was in my situation, how would they go about securing all this. Would they upfront 20% in deposit and secure the land and build. Or dump every bit of savings into the build then once that's complete refinance and use the equity to purchase a rental home? We are early 30s with young kids so we are still working with decent income and not relying on having a super low mortgage of that helps the opinions.

Thanks in advance.