It’s no secret that painting black on miniatures is hard. I learned a few tricks at GenCon, the two that stick with me are: highlights should be about 1/2 the size of normal highlights, and highlighting from black to grey often just ends up looking grey - it is best to tint your black highlights with another color like blue (cool) or brown (warm). Very few things in life are truly pitch black, tinting blacks can help differentiate materials on a model and reflect the world around the miniature.