Ah, research methods. The bane of many a student. The old assumed knowledge trick.
Luckily, VCAA (even with its website's new and confusing interface) outlines precisely what you need to know on
page 22 of the study design.
A formulated method? Honestly, I would just try to work through the dot points in the study design. Some people don't like notes, but I'm a religious note taker, and I find it very helpful. Use your textbook or anything else you have, and just summarise it. And then summarise that. And then summarise that. And so on. Once you have a solid understanding of the content, you can start applying it to various situations or case studies.
For things like experimental research designs, you can have advantages and disadvantages. For things like ethical principles and professional conduct, you can have why each point is important, and perhaps an example of it being breached.
There are lots of resources around for research methods, but personal message me if you're struggling to find anything.