Prompt: masterpiece, best quality, girl, light blush, white colored eyelashes, sailor suite, serafuku, waving, five fingers, show hand, in summer, on the beach, sea, 
(thick outline), flat color

(I don't know why Civitai mark this one as "txt2img+hires", this is a "before hires" one)
Negative prompt: (worst quality, low quality, extra digits, loli, (loli face:1.4)), (greyscale, (monochrome:1.1)), (tan,text:1.2), nostrils flare, extra fingers, fused fingers, missing fingers, (bad-hands-5:0.9), hand distortion, bad hand