What is one way to analyze a source for evidence in support of claim

The author's historical context can be relevant. For example, a passage from the bible will have different biases than that of an Islamic scholar. This highly affects what their words will mean and what they'll omit/include. Both of these allow you to form a fully sourced claim and rebuttals in your essay or short response.

after defeating german forces in north africa allied leaders turned their attention to "italy," since this was the location that made the most geographic sense before invading northern europe via france.