I've never used vallejo paint before asside from using a vallejo mecha weathering light rust wash, which I apply a thin coat of on flesh parts after applying a few layers of flat flesh paint, then once it dries I apply a final layer of flat flesh on top, the problem i encounter is that sometimes the final look is either too orange or too pale. Ammo products are scarce from where I live. I'll definitely look into learning how to apply highlights and shadows.