To write good essays in english you have keep the following points in mind :-
1. Main / topic idea sentence should be clear, correctly placed and is restated in the closing sentence.
2. Paragraphs should have three or more supporting detail sentences that relate back to the main idea.
3. Paragraphs should have no errors in punctuation, capitalization, and spelling.
And also try POWER writing i.e.
P Plan (Plan what you have to write and the main points)
O Organize (Organize the stuff i.e. what will come first and what will come later.)
W Write (Write the matter)
E Edit (Edit it.)
R Rewrite (Rewrite it.)