Make sure that, before your exam, you have planned your answers to a range of questions which have come up in past papers/may come up in the future. Your plan should include, primarily, your judgement and how you expect to be able to argue/form a case for this! (Think of yourself as a lawyer in a courtroom).
So, the most important thing is your judgement, and them you should plan 3 points which can help you to argue in favour of this. In each point, relevant dates should be added into your plan (your plans can help you to revise the dates you should know!) as well as pieces of historical evidence which could help.
With each point you make, you shall need to bring in counterevidence, which could be brought against you (again, like the opposition in a court of law), and you need o defeat this, by offering stronger evidence which favours your opinion. However, you need to make sure that the counter-evidence you are using isn't the weakest there is - although this is easier to defeat, your marker will be well aware that there is stronger evidence which opposes your view which you have just ignored. Make sure you're not taking the easy way out!
The conclusion should reinstate your judgement, state how you think you have shown evidence for this and why you think it is the right view to hold. It should be snappy, but not rushed - a conclusion is very important in academia, and at A Level, this is a good thing for you to practice!