For Engilsh Essay make outlines of different topics.Choose topics of social issues first.Try to make comprehensive outlines and start writing on your points.
I got 47 marks in last year topic was Climate/Global warming related.I wrote simple words with simple points and some facts and figures.It was not an extraordinary piece of work but yet it gave me good marks.Try to pass compulsory papers as they dont give high scores.
Its my experience it can differ from person to person.

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The only true wisdom is knowing that you know nothing