Plan well in advance before you start it-----don't write straight away, think over your main idea before you start it.
Jot down briefly the main ideas, supporting paragraphs and points-----build a sound structure before you fill in the details.
Keep your sentences clear and simple to express your ideas-----avoid complex words that you are not familiar or comfortable with.
Stay focused on the main idea of your essay-----Trim down the redundant details that are irrelevant to the core idea.
Re-examine your essay in the end just to make sure it is overall smooth and things make senses-----You may always make a few spelling or grammar mistakes while you're writing your essay. Hence it is a good idea to try to read through your essay once more and correct them.