like above, write solid essay plans and then know the content to the extent to which you can reduce to a few words on a palm card. look at the themes and challenges closely of your national and international section, have strong judgements for all of the dot points with a prepared thesis and relevant content you will use to argue that point. For both the national and international study, I don't believe it is necessary to use historians... your judgement should be solid enough and thus namedropping a historian is not really needed...
For the personality, memorise section A (their background, education, rise to prominence)
and for section B, have a prepared judgement and the relevant historians you will use to argue this, but make sure you can adapt to any question you are given. For my exam last term, I had to drastically change my thesis and use a lot of historians I didn't want to use to answer the question and thus achieve full marks.
For WW1, just practice all the content and go over source analysis!! Good luck!!!