A flat primer is a good idea. Paint is less likely to "run away" in an uncontrolled stream. Glosses are only for silk or wet cloth, wet skin/hair (oily=wet too) Semi gloss can even be too shiny. Satin or flat is best for cloths and most skin. (eyes get white gloss, lips maybe a gloss, maybe not...lipstick gets gloss. (if you go that small. A contrasting wash over faces to accent the facial folds&knooks is ok too.).. I start with eyes, dark accent line at the bottom, then white, then color, then flesh... teeth, flesh, then lips, unless sunken, then lips before flesh..etc. etc. You will likely have to trim a small brush or two for various stroke types. Count on messing one or two up learning to trim them. I prefer natural brushes for most fine work. I comb them wet, and treat them to mineral oil and or mineral spirit soaks to help keep them soft. A fold of paper, plastic wrap, foil, etc. can press a flat tip or taper back into a drying brush as well. Good luck.