Q: Is there any specific study order that you recommend for task 2?
A:So here's what I think:
1. Essay structure and paragraphs
The first thing to do is find an essay structure that works for you. You probably know that I prefer to write 4 paragraphs, and maybe you've seen how I write 2-sentence introductions, 5-sentence main paragraphs and 1-sentence conclusions. Try this: take some essays that you have already written, and rewrite them so that they all have the same number of paragraphs and sentences.
Take several different questions, and practise planning ideas. Then spend some time focusing only on introductions e.g. write an introduction for five different questions. Then do the same with conclusions. Then try writing different types of main paragraph e.g. an 'advantages' paragraph, an 'opinion' paragraph, a 'problem' paragraph etc.
When you are confident that you know how to write an essay, it's time to start working through as many common IELTS writing topics as possible. Even if you don't write a full essay for each topic, you should at least plan some ideas and opinions.