The following advice is from The American Library Association
‘Once you have identified primary sources, it is necessary to read and examine them with a critical eye. It is important to consider both the source itself and the time in which it was created. Remember, too, that sources exist in different formats. Below are some of the questions you may ask about the nature of a source:
• What is the source and what is it telling you?
• Who is the author or creator?
• What biases or assumptions may have influenced the author or creator?
• Who was the intended audience?
• What was the significance of the source at the time it was created?
• Has the source been edited or translated, thus potentially altering the original intent or purpose?
• What questions could be answered using this source?
• What, if any, are the limitations of the source?
• Does your understanding of the source fit with other scholars’ interpretations, or does it challenge their argument?
Consideration of these questions will help you analyse and interpret your sources without overusing and relying on too many direct quotations.’
Measuring Worth is a useful tool for finding out how much various things cost or were worth in different time periods. Also has conversion tables to change imperial into metric.