By skyforbes 
Tip 1. To quickly iterate the prompts and visualize the result, I asked Gemini to give me a grid of three horizontal images. Then I can pick out prompts that work well, and generate a single image.
Tip 2. Sometimes, Nano Banana goes wrong with the aspect ratio. The fix is to attach a reference image for the layout grid (not for the style or the content).
Problems: It seems Gemini is switching among Nano Banana Pro and the previous model. Sometimes, it outputs 2816×1536 resolution, other times it's 1024×1024. I am having a hard time trying to control the aspect ratio while maintaining the same style and aesthetics. I made do with the 1024 resolution, batch saved the images, cropped to horizontal aspect ratio, then upscale with Aiarty image enhancer by x2 and restore details, so it maintains clear when viewing on large screens.
Prompt example:
Give me three horizontal grid of images (refer to the grid layout of the attached image)
{Image 1
A plush handcrafted still life inside a miniature winter world made entirely from yarn and felt.
A knitted serum ampoule stands upright next to a tiny wool snowman with stitched eyes and a crochet scarf.
The ampoule features embroidered gold details, and a droplet of translucent wool “serum” rests beside it.
A pastel felt background shows stitched snowfall lines for added holiday charm.
Image 2
A yarn-crafted body mist bottle sits on a tiny felt fireplace mantel decorated with miniature crochet stockings.
The bottle has delicate ribbed stitching and silver-thread label embroidery.
A soft puff of white wool “mist” hovers above, shaped like a drifting snowflake cloud.
The mantel is framed by plush red felt and tiny yarn holly accents.
Image 3
Three plush lip tint tubes crafted from yarn and felt sit inside a small felt Christmas gift box lined with soft wool.
Each tube has festive embroidered patterns resembling wrapping paper.
A tiny felt ribbon is stitched onto the lid, and wool “snow” tufts spill from the edges.
The scene rests on a pastel winter-blue felt cloth.}