IELTS Writing Task 2: how do you learn from sample answers?

How do you actually use sample answers when practising? Do you write your own essay first and then compare, or read the sample before starting? I’m a bit unsure what to look for apart from vocabulary. If the sample uses completely different ideas, how can I tell what I should improve in my own answer? Would like to hear what people do with one sample essay. Read it, rewrite your own answer, try a similar question? I don’t want to just memorise it and get stuck when the question changes.