Recommended sampler: UniPC (Actually, I've only made it with this, so I'm not sure about anything else)
Recommended Upscalers: R-ESRGAN General WDN 4xV3, R-ESRGAN 4x Anime 6B
Mandatory prompt: Not really, but it feels like it comes out well when using EasyNegotiative.
Caution: Finger batting average not guaranteed :)