Practice writing many essays instead of one.
Give yourself a new question every week, and try answering it to the best of your ability. At the beginning you will suck harder than a recondensed singularity, but after a while you will slowly get less incompetent.
This forces you to think on the fly and come up with relevant, tailored responses to any number of different situations. The more you do this, the stronger the mental channels which govern these analytic processes (this is proven by #SCIENCE). In other words, practice makes permanent.
Think of English as a sport: you're training your muscles and building them up over time. You can't predict what your opponent will do on the day - but you can prepare your mind and body to be ready to take on most whatever they throw at you. The "and body" bit is not superfluous: handwriting stamina is one of the main killers in the exam room.
Delta Education's advice is probably well-meaning but also dangerous: the "tweaking" approach prepares you a little bit more for variations in questions and approaches, but not much. In fact it can breed a false sense of security that you're answering the question when, in fact, you're just packaging up a turd in a shiny new wrapper.
strawberrye and superesse know what they're talking about. Trust them.
