I think I'm going to alternate between writing and drawing topics for this series. ^^
So, black hair...since I'm not a painter, I'm not going to bother showing any visual examples (I literally just draw blobs...not much to explain there); I'm just gonna talk about it conceptually.
The most important thing to understand about black hair, if you understand nothing else, is that it tends to defy gravity. "Typical" hair physics don't apply until we put it into braids; otherwise it tends to stick out perpendicularly to the surface of the head (this is why afros exist). Think of it as millions of tiny, delicate springs.
There are different types of black hair, though (like, there's a literal classification system...I think I'm 3C). I don't know the details because I don't care much about beauty stuff (9w9) but basically you can think of it as differences in the 'stiffness' of the springs.
Some people have thick, tightly coiled springs that defy gravity almost perfectly (you usually see this in mens' styles) and some have loose springs that are more like 'wiggles': they still have volume, but the longer they get, the more they bend to gravity's will (often seen in women's styles).
By the way, the men/women dichotomy isn't a biological thing; there are plenty of women with "thick springs" and men with "loose springs". I'm just referring to how they're usually portrayed in media, women especially. I think I can count on one hand the number of African American female characters I know with unbraided hair that isn't 'loose springs', or completely straightened. There's a bit of stigma about it, but that's probably a conversation for another time. ^^;
I think I've rambled enough; gotta leave things for other people to say. ^^; If I had to leave you with one tip, it'd be this: USE REFERENCES! I don't say this often, but this time I'm saying it and I mean it. Use references when you design black hairstyles!
Most people (myself included) instinctively know how to design "white" hair through cultural osmosis; it's literally everywhere. I have about 6 million anime hairstyles catalogued in my brain that I can toss at a new design with minimal effort.
But when it comes to black hairstyles I have, like...10? Maybe? My point is that if you want to expand your repertoire beyond 'afro', 'puff balls', and 'wavy mountain', you gotta put the time in and do research. There's lots to learn out there.