you should always state in the first couple of lines what your answer is the the question. Ensure you have answered within the first paragragraph, is you don't you will lose marks because of it.
Make sure you sustain your argument by always referring back to the question. Make sure you are constantly reinforce your views with evidence.
To increase your marks make sure you also develop your essay with involving another point of view, usually the opposite view and say "even though a lot of people believe this point of view, some people also believed the opposite" you may wish to go into detail but remember always back up yoru points with evidence.
If you don't you will do get any higher that a C grade at GCSE and you will not get anything Higher than a D at As Level.