The most common purple problem is that people are using a "candy apple red" and a "sky blue" when mixing. This red is not a primary, it's actually a red orange, meaning when you mix it with blue, it comes out murky. Sunset red by Vallejo is a better choice since it's closer to magenta. But for this specific one- Violet red highlight (like Mr. Dragonsreach suggested), purple for base,and violet with either a darker blue or tiny amount of black. Hope this helps!