Ah, thank you. Mostly I go by feeling aka what "sounds good" in English but with grammar it can be tricky.

Had + verb = One action in the past with a definite beginning and ending. Such as: "I had walked to the store, but it was closed."

So if someone was doing something right now that I write in present tense and their thoughts featured a recollection of a past event, one that is definitely finished I`d use the "he had done so and so"?

And then of course there is past dialogue. *drops dead*

What I never really know what to do with things that "linger", like feelings. Say if I want to establish that person A had a certain effect on person B they would presumably still have, only A and B currently don`t interact so it`s all technically in the past.

Sorry for the grammar bombardment. *g*