Sometimes knowing what NOT to do can be helpful: Here's 7 things to AVOID in your latest A Level essay!
Using needlessly long quotes
Your essay will only be marked on your own words and it's those that the examiner wants to read. While quotes will be necessarily, keep them short, to a minimum and relevant. Filling up your word count with needlessly long quotes is pointless: Just paraphrase in your own words.
Unless you've been specifically asked to summerise something in the question, just giving your own synopsis of a book, film, piece of work, etc. isn't an essay. Simply regurgitating a plot, even if it's in your own words, won't get you many - if any - marks.
Including no references
References are key to most essays, certainly at University level. If you make a claim, back it up with evidence!
Not checking your spelling
Another one that shouldn't really need to be said: Make sure to always check your spelling, grammar and punctuation. Read through your finished essay a few times and always re-check if you make any changes.
Get together with friends or family and have them read over what you've written as a fresh pair of eyes will be better at spotting tiny errors.
Ignoring the question
You can write the best essay known to man but if it doesn't actually answer what the question asked then you can bet no marks are coming your way. Always read the question carefully and make sure you actually answer what was asked rather than what you hoped or wanted to have been asked.
Not making sense
A good essay starts with a plan else you'll end up with an unorganized mess of ideas that either don't flow or just don't make any sense.
Leaving it to the last minute
Now this REALLY should go without saying but leaving it to the last minute will lead to a clearly rushed essay that will never be the best it could've been. You'll usually have weeks of notice before your essay is due so get started at the earliest possible opportunity if you want to make sure you get top marks.