Prompt: best quality, masterpiece
Negative: (worst quality: 1.4), (low quality: 1.4),
* Adjust the strength and prompts to your liking, but keep in mind that the negative prompts are very important!
** Use (nsfw:value) positive/negative prompt as needed.
*** Consider adding age tags like: mature female, teen etc.
Most samplers work pretty well, so try out what works for you and pick your favorite.
I'm personally a huge fan of DDIM because it's very fast and I can test prompts and seeds very quickly and make adjustments without much delay.
My "personal" basic settings:
Sampler: DDIM
Steps: 30
Clipskip: 2
CFG Scale: 10
VAE: Included
HiRes fix: R-ESRGAN 4x+ Anime6B
HiRes Steps: 25
HiRes Denoise: 25
Upscale by 1x for prompt or seed testing and higher for final results.