IELTS

If you really want to impress the examiner, use the past perfect tense. It's not easy to use and to be honest I only ever hear students using it in the wrong way! But it's not impossible to master. And if you are looking for something higher than a 7.0 then you should really try to use it

We only use the past perfect tense when something happened before something else. So you need a reference point in the past, which is usually a verb (some action) or a time (time expression)

Let's extend that example from the articles on perfect tense with the past perfect tense:

Q: "Where do you live?"
A: "Right now I live in Taipei; I moved here at the end of last year -- I'd been living in Tai Zhong for several years because I studied there. So I've been living here, in Taipei, for a year or so."

The reference point in the past is "moving to Taipei" and anything that happened before that needs to be in the past perfect tense.