Hey!
Try different things out:
- roll Oracles and place the results in them. Figure them out later
- put random things that come to your mind without being specific: pirates!, an earthquake feeling, headaches, pain in the back, a friend, cultural shock. Play around!
- use things from the lore of the game your playing, elements that your characters already know exits in the universe (Green Goblins, Baratheon mercenaries, A sorcerer, whatever the setting gives, etc)
Then just let it be, the idea of plot nodes is to inspire yourself, and that they show up by using Random Prompts later.