There will be 2 parts to this - question 1(which is an essay question) will have you answer either (a) or (b), and question 2 (the source parts) will ask you to answer both (a) and (b).
Question 1 (the essay question) should be answered roughly within 20-25 minutes, allowing you to allocate enough time for question 2 where the majority of the marks are given. 2(a) should be answered within 20 minutes, 2(b) within 40 minutes.
Look at the focus of the questions, bringing in the dates and what information the sources are giving you. For question 2(a) for example, if a question asks "how useful is this source as evidence for a historian studying ...." you need to look at the content (what does it say), the value of the source (who wrote it whether it was primary or secondary, when was it written, why was it written i.e. motive, what type of source it is i.e. speech delivered to an audience often with a prupose in mind, a private letter which often gives personal opinion, where it was written and whether we can trust the opinion of who wrote it - how reliable is it?), and the limitaitons of the sources (in what ways is it limited, for example the date - if it includes a specific time frame and the source does not tell us all the information within this time frame and only gives a small perspective, then you need to bring in outside knowledge of why this will not be useful to an historian who is looking at the whole picture. Explain what the source does tell you, but also what it does not and thus why it is limited.
For question 2(b) you need to approach this as an essay style question with an introduction, main argument and conclusion. The introduction needs to address the question head on and establish what your argument is using your outside information, all the while referring back to the sources showing why this is your arugment. You need to link both your own knowledge and the information in the sources in order to gain the top marks. Refer obviously to the sources, using phrases like "as indicated in..." and "suggested in source..". The information above in 2(a) still needs to be repeated here in order to make your arugment stronger, emphasising the limitations on a source which is not useful to your arugment. As well as this, you need to apply interpretation to your answer, using historical opinions of others, which may be within the sources, or within your own knowledge, such as contempoary opinion which can be applied to the question. To conclude the question, repeat again overall what your interpretation is and show that throughout your essay you have been able to back up your argument with evidence. There is no right or wrong here - evidence will gain marks.