War, hatte, konnte
In everyday speech, sein, haben, and modal verbs often use Präteritum. Ich/er: war, hatte, konnte, musste, wollte. Wir/sie: waren, hatten, konnten. Other verbs often use Perfekt in conversation.
Understand the idea
Präteritum is a simple past tense: the lexical verb itself carries the past form. It is common in written narration, and sein, haben and modal verbs also frequently use it in speech. Choice between Präteritum and Perfekt depends partly on register and region.
Build it step by step
Learn war and hatte early. Regular past forms use a -te pattern; strong verbs change their stem. Ich and er/sie/es often share a past form. Wir and sie plural share another form, while du and ihr need their own endings. The present-tense stem-change pattern does not predict every past-tense stem.
See it in a sentence
Gestern war ich müde.
Wir hatten keine Zeit.
A useful memory aid
Practise short accounts with war, hatte and musste first, then compare them with their present forms in the verb tables.
A common trap
Do not combine a bare Präteritum form with a present auxiliary as though it were a participle. A simple past sentence needs its own finite past form.