the most important thing to do is learn to contour, and learn to blend. Also, practice. Shimmer matters, it makes areas lighter than you see by eye because of the flash. If it's a pale shimmer and you MEAN to hilight that area, then it's fine, but if you shadow that you are contouring with has shimmer, that's gonna show lighter than you see it and that may not be what you intend. B+W is all about light and dark, and if you can't have ultimate control over your products and you are not yourself a photographer. I'd stick with matte everything. That way you know how it will look in pictures. With experience or if you are a photog, you can control the situation better. Also be aware, for headshots for modelling or acting, what the agencies want is super natural, super bare-faced perfect skin looks. Especially in B+W. Concentrate on the skin and super subtle contour effets.