Use the acronym JACK
Two paragraphs one about source A and one about Source B
JUDGEMENT State how useful the source is for the given enquiry
ANALYSIS Make an inference about the source by either picking out a direct quotation or describing the image Analyse the provenance (why might it be made? Is it propaganda? Is the date important)
CONTEXTUAL KNOWLEGDE Compare the content of the source against your own knowledge – how accurate is it? Use specific detail
Also when finding the strengths or weaknesses of the source consider who wrote it, when it was written, why was it written. If it was a photograph or painting you consider the same things but different circumstances
Hope this helps! Ask if you have any questions xx