Here's my tips. Not sure if it will work though.
Keep the seed for consistency, in comfyUI I need to keep it consistent across 2 generations. Take care with eyes and hands.
use simple words that cost one token mostly, try to keep within 75 tokens. use (masterpiece hires, best quality), then prompt.
SD15 is different than sdxl in tokens. sdxl is smarter, but still comma sep fairly simple concepts.
First generate several images. Lora's might help. IP adapter face might work thereafter if you have several images, or you need to train a model.
Focus on the person, keep the background simple. because if you can remove background, than you can use the images on multiple backgrounds.