How do I know when to use which past tense in French when I'm translating/writing?

The easiest way to correctly use different tenses, and particularly past tenses, when writing in French, or translating into French, is to remember the different values linked to each tense, in the context of the sentence they are being used in. The three main tenses you will encounter in the grammar of French texts will be the imparfait, the plus-que-parfait, and the passé simple.Imparfait : description / regular + repeated actions / ongoing actions ex : Le maison était vieille et insalubre / Tous les mardis, j'allais me promener / Je marchais depuis longtemps.Plus-que-parfait : a past event or action that is still relevant to present context in which the event is being recounted.ex : Pendant longtemps j'ai cru que le Père Noël existait vraiment.Passé simple : a one-off, sudden event that has no connection to the present.ex : Soudain, il sortit du placard.