Quick tip; achieving amazing reds. (Patreon)

This create was painted with a base coat of black, white zenithal spray to help with value, then I used several thin coats of a darker red (this can be blood red from scale 75, Khrone Red from GW, Gory Red from Vallejo) to achieve a consistent result across the entire miniature. 

Instead of adding white and black for high lights and shadows (or lighter and darker hues from your paint range) try mixing a touch of violet for the shadow and some orange/ lighter skin tones for the high lights. It's a small change, but it may just be the next break through you were looking for.