LORA weight 0.8 works great, but feel free to adjust the strength to your liking
Prompts that I usually used:
Older version:
aMei, long hair, white hair, braided ponytail, hair over one eye, braided ponytail, purple eyes, black dress, long sleeves, puffy sleeves, turtleneck dress, wide leg jumpsuit pants, pants tucked in, front braid
Younger version:
bMei, white hair, ponytail, parted bangs, hair ornament, scrunchie, purple eyes, black shirt, grey necktie, dark purple skirt, long skirt, high-waist skirt