I recommend including series + artist name in the prompt, I did not include it in my captions but it helps keep the style consistent.

Check my samples for full prompts, but you should at least include:

Ponytail: kokuy0u, ponytail, japanese clothes, tsugumomo, hamada yoshikazu, official art

Loose hair: kokuy0u, long hair, japanese clothes, tsugumomo, hamada yoshikazu, official art