Hi Trevor! I'd like to help you with this. I'll give you some pointers here, but if you'd like more one-on-one assistance, please message me.
Basically, you want to use preterit for simple, completed actions. A trigger for this is when you have a day, date, or specific time. For example: En Hawaii yo me quedé (stayed) en el Hotel Ritz.
Use imperfect for repeated actions that occurred over time: Todos los días iba a la playa y me bañaba en el mar.
As far as what to write about, first think about it in English! Maybe you'll have to be creative and make some things up if you run out of true things, but come up with some things you did on a consistent basis (imperfect) and some things that are completed actions or expressions (preterite: ex "Me gustó mucho el viaje a Hawaii").
Hope that helps!