"I was thinking more along the lines of doing some research" - in this context "along the lines of" is used to present a different idea. e.g.: Person 1: "For the project, why don't we start by making a presentation?" Person 2: "Well, I was thinking more along the lines of doing some research." In other contexts, it can be used in a way which means 'similar to'. This example is from the Cambridge Dictionary: "They're ​campaigning for the ​electoral ​system to be ​reformed along the ​lines of (= so that it ​becomes ​similar to) the one in Germany." Hope that helps!

'Along the lines of...' means 'in the general area of...' or 'something similar to...'. This is one of the English language's many 'hedge' devices. These are words and phrases made to make our language more vague and general. 'Kind of', 'sort of' and 'like' have the same effect.