Do you have any suggestions for writing a good fan fiction?

Hey, I’m writing an MCU fanfic and I’m having some trouble writing a scene and I was wondering if you had any tips or suggestions. I’m trying to give this scene a nostalgic feel but I’ve got writer’s block and could use some ideas.<br><br>The scene I’m writing is a flash back scene from the first time Peter met Happy and saw the Avengers Tower… It’s supposed to be a happier scene, showcasing the first time Peter met Happy and the time he saw the tower. I don’t know, any suggestions?