Most modern Australian homes use timber frame construction, with plasterboard fixed over timber studs. This means you’re usually fixing into plasterboard with studs sitting behind it every 450–600mm.
For anything heavy, the best option is to screw directly into these studs, as they provide the strongest and safest fixing. This is especially important for items like shelves or curtain brackets, where plasterboard alone isn’t strong enough to reliably support the load.
A stud finder can help locate studs through the plasterboard. Here's a helpful guide: How to use a stud finder.
If studs aren’t in the right position, the next best option is an spring anchor. This type of fixing spreads the load behind the plasterboard and provides the strongest hold when fixing directly into it. For very light items, plastic anchors like Wallmates can be suitable, but they are not designed to support heavier loads. - MitchellMc
Screw-in anchors can hold around 10kg each and you don't need a stud. Toggle-anchors are similar but have an extra wing that drops down and braces on the back of the plasterboard. They can take 20kg each. Again, no stud needed. Butterfly or toggle-anchors are great but they need quite a large hole so no good if you can't hide that.
There are also hollow-wall anchors but in my experience they can be a bit hit-or-miss.
The real trick when anchoring into a hollow of a plasterboard wall is to fit the anchor very carefully and don't overdrive or over-tighten it. Plasterboard is very unforgiving and basically disintegrates if you stress it too much. – Adam_W
My recommendation is to use a hollow wall anchor that grip from behind the plasterboard, such as spring toggles. Alternatively, hollow wall anchors stay in place allowing you to remove the screw as needed to fix the item to the wall. It's a matter of trial and error in making small adjustments to the screw head height until the holder fits very snuggly against the wall. It can't be loose. – Nailbag
I would strongly advise against installing anything heavy like a cabinet or television using plasterboard anchors. These items should be screwed into studs as the plasterboard is not structural and the potential for the plasterboard to fail and the item to fall off the wall causing injury to its user is far too high. - JacobZ
