The preterite tense is probably the most difficult tense to learn in Spanish for two reasons:
1) its endings don't follow such a nice 'pattern' as the endings in other tenses
2) there are quite a few irregulars
But don't worry! I have a few tricks and tips to show you that will help you to see that there are some patterns in the irregular verbs, and actually you can 'recycle' the endings from tener for most other irregulars!
Below you will find a free downloadable 'cheat sheet' which shows you all of the irregular verbs you can use the tener endings with. You just need to learn their irregular stems. It also shows you a few other patterns to make the irregulars seem a little less intimidating, as well as a trick to unlock dozens of other verbs.
For some guidance on how to use this 'cheat sheet', and an explanation of the patterns in the preterite irregulars, you can watch my video below (you can also see it by clicking the link in the pdf).
That's all for now. I hope you find the 'hacks' and the 'cheat sheets' useful, y ¡espero que te vaya muy bien con el español!