Your essay should start with you stating the subject that you are going to be talking about. You should then quickly tell the reader what you are going to say about that subject, the main points of your piece.
Good Flow is essential to clear writing.
Your next sentence should always be one that the reader would naturally expect to see having just read your previous sentence. Either write about the subject of the previous sentence or the object. Do not suddenly start writing about cows. Don’t switch ideas until the next paragraph.
One paragraph should contain only one idea.
And please remove all information from your writing that doesn’t contribute to the ideas (points) you are attempting to convey to the reader.
In summary, you should first decide the subject of your essay and then the points you wish to say about that topic. Think of a logical way to present your points. Then concentrate on writing only about those points—and nothing else.
And when you edit your essay, remove everything that would be obvious to a reader or superfluous to your main points.
And when your teacher reads your piece, you will get an “A” if your essay flows well and the teacher easily understood the main points of your piece.