What is your advice when trying to understand the significance of similarities between two passages of Scripture?

This text is from a letter written by David Gooding.

I have found in my own studies that it is useful, when I have seen certain general similarities between two passages of Scripture, then to get down to the exposition of the details of the two passages concerned. For, when we do that, the very proportion of the narrative in each case will guide us to what in the thought flow of the passage is the dominant idea or ideas.

The second thing I would do, when I get the hunch that two passages may be related because they have certain things in common, is then to ask wherein they differ. The right hand and the left hand of a human body have obviously much in common, so that if you put them together in a certain way they look exactly the same; but they do have differences, and those differences are even more important than the similarities. And that kind of thing can be true of passages that are marked by similarities: their differences then will lead us to what is the special point of each narrative.