The audience outside Australia for a blog about life in Sydney will be very small. So if you're looking for a large audience, you might want to blog about something else or else address people in Australia primarily.

For attracting an Australian audience, try this:

Carry pen and paper around with you for a week or two. Every time you see, hear, or remember something distinctively Australian or unique to Australia, jot it down. Even if it's just a turn of phrase, a scrap of local news, or a business establishment, these are elements that you could weave into your blog posts – keywords that might attract passers by who have searched for similar phrases.

For attracting a non-Australian audience, such keywords will be too obscure to magnetize search traffic. You'd have to research what search queries are commonly entered by tourists planning an Australian vacation.

2 very different approaches for 2 utterly unrelated audiences.