How is the best way to structure an English essay?

They key thing to remember is P.E.E (Point, Evidence, Explanation). In your introduction you should start of introducing what you are going to discuss. Then each paragraph should be a different point, for example if you were writing about whether King Lear is mad or old your introduction would introduce this, then your first paragraph may be a point on why he is old and then your second paragraph will be why he is mad, or another point on why he is old. Within each paragraph you will firstly make your point, then support this with with a quote from the book or play, then analyse the quote. In your conclusion, you will then come to a judgement from your points on whether he is or isn't mad.