SD almost sorta kinda recognizes Nicki Minaj which has actually made getting a LoRA that'll produce a good facial likeness pretty difficult. I've adjusted my training data and tried this a few times with LoRA and Textual Inversion training. I've also tried it as a custom token vs. having the LoRA ride "on top" of the default SD data for her. It's still a little finicky but I think this version is good enough to release.

Since it's operating on top of SD's own understanding of Nicki Minaj it tends to like high-ish step counts (40+) and low-ish strength (under .5) but mostly it's just a bit of a moving target depending on the rest of the prompt. There's almost always some strength that gets you a good likeness but it sometimes requires some experimentation to get there. My suggestion would be to start around .4 strength and fiddle with it from there.

Last wrinkle is that it can also produce very light skin especially when combined with other LoRAs or strong embeddings. Use "black woman" or "African American woman" to combat that.