1. Form and meaning
Präteritum is common in written narratives and with sein, haben and modal verbs. Plusquamperfekt describes an action completed before another past event: hatte/war + Partizip II. The auxiliary is chosen in the same general way as in Perfekt.
When you study this pattern, identify its communicative purpose first. Then check the verb form, case and word order. German clauses are easier to control when you learn the connector together with the sentence pattern it requires.
Example 1: Früher wohnte ich in Bonn.
Example 2: Als wir ankamen, hatte der Film schon begonnen.
2. How to use it accurately
Build your own sentence by replacing one part of the model while keeping the grammar pattern unchanged. Pay attention to the finite verb, commas, noun capitalisation and the case required by any preposition. Read the sentence aloud and compare the meaning with the English explanation.
Study strategy: Make one affirmative example, one question or contrast, and one sentence connected to your own life.