Source questions can be scary, particularly as the short time limit makes you feel that every word has to count. To feel more comfortable when analysing a source, the most important thing to keep in mind  is 'what am I being asked to do exactly?'. And the answer to that question is that you, as a historian, are being asked to use your expert knowledge to explain the significance of a historical doccument, through analysis and context. Whilst that may seem daunting, this approach allows you to focus your relevant knowledge on the source (and not stray off topic - something examiners hate). 

GOLDEN RULE: The first thing you should do is read the source carefully and actively (highlighting and jotting down ideas). This will help you match your relevant knowledge with the specific source that is in front of you. 

How To Structure My Response

1) Context - briefly explain who wrote the source, when was it written, and why.

2) Analysis -  Over two paragraphs, you should pick out 3-4 key elements of the source and explain their significance. A good technique is directly quoting words or phrases (not full sentances) from the text, as this helps you direct your analysis entirely upon the source. 

3) Broader Analysis. If you have time, try to end your analysis with a few sentances on how the source relates to the important themes in the topic as a whole. For instance, if you are studying a letter written by a leading figure in the American Revolution, what does the source tell you about methods of protest and during this period? It is good to leave these ideas to the end as it allows the main analysis to focus on the specific text, which is your main job after all!