Writing style should vary according to the requirement
Are you writing a descriptive personal account?
Write naturally and not with the intention of impressing the teacher. Continue writing only when the picture keeps unfolding in front of your eyes. This will help your style to’ show’ rather than ‘tell’.
Are you planning to write a business letter?
Be sure to come straight to the point .There need be no introductions, elaborate descriptions, detailed narrations of past or present incidents. Remember to convey the central idea of your letter straightaway. Do not branch out into episodes.
Are you writing an imaginative essay?
I f you have to write an imaginative essay narrating some imaginary experiences of a soldier or a pilot, then you are likely to face a problem because you may not have fought a war or may not be able to visualize such a situation. For this special reading and collecting information is required. You can read up the narrations of a soldier or a pilot and create your own ideas and make up the essay.
Check your grammar.
The common mistakes made by students are in the use of direct and reported speech, and the wrong use of participles and verbs. Do not rely on your MS Word spell check but know your rules well. For example “have written” is the correct usage and “have write” or ‘have wrote’ are wrong usages.
There is a vast collection of all sorts of essays in this academic library and you can read through the best to get an idea.