If you have a choice of topics, choose one you are interested in.

I don’t know if you consider this the easiest way, but it is a practical way.

Write your first draft, and then rewrite it.  Give this 2nd draft copy to the teacher and ask them to read it and make comments before you prepare your final version to hand in for a grade.

I’ve always found that punctuation, spelling and grammar pull grades up.

I cannot tell you exactly what is the easiest way to get it but if you really want to have an A – deserving essay, choose an interesting topic that you know well. Research about it and include some additional details that not everyone knows – this is to add some excitement to your essay. Having all the information needed, let your heart speak out on your chosen topic. Make it short and simple, and do not forget the basic rules in writing.