IELTS Writing task 2 is the same task for Academic and General IELTS. The candidate will be presented with a specific topic and asked to write an 250-word essay about it. The candidate should normally spend 40 minutes on IELTS Writing task 2.
How to write IELTS Essay?
1) Determine your opinion on the topic

Usually, IELTS essay is one of the following types:

Giving your opinion
Agree/disagree
Suggesting a solution
Pros and cons
Depending on the topic, decide what is your opinion on it and why. Have a clear position, don't hesitate between two opinions! Then find examples you will use for this task. You should spend a few minutes on planning.
2) Write an answer including an introduction, body, and conclusion.
3) Style your essay

Use various words and structures, linking devices and avoid repetition.

Do not use informal style and avoid irrelevant information, you will receive less points for your work.

Also, don't forget to write at least 250 words, writing less will affect your mark negatively. You should aim at 260-280 words. You won’t get more points for a longer essay.
The Official Marking Criteria