first read rules of essay writing from any english book.. high school english grammar by wren and martin and exploring the world of english by syed saadat hussain shah will be worth reading for this purpose...

then start working on paragraph writing.. along with it you may practice paraphrasing as well... (for atleast a month or so)

then do brainstorming and make outlines of essay,,,(for ten days)

write short essays of 250 words or more... get them checked from any good english teacher...(again regularly for a month)

slowly and gradually increase the length of your essay... continue to get them checked from a css qualified person or from any teacher...(till the last day before you appear in the exam)

however, develop a reading habit,,, it will help you to write logical essays with full of information...

regards

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"pattering your life around others opinion is nothing more than slavery"