Result of my experiments described in this article.
Usage
Scheduler/Sampler: Euler A + Beta
Steps: 30
Positive prompt: No need for Quality Tags, "Flatline, Flat vector illustration, Black outline, Vivid colors" can be added for a more flat result.
Negative prompt: IllusN3g
Be warned: this checkpoint has been messed up a bit too far and following prompts is not his Forte. But it will generate fun and unexpected results :D
If you prefer using a LoRA, check CuteIXL Style