Redhead — Bust

: Focus on the undertones. Many redheads have fair skin with pink or blue undertones. Incorporate freckles as varied, non-uniform spots to add realism. Styling & Grooming Guide

For developing a personal style "bust" (head and shoulders look): Redheads Guide to Eyebrows redhead bust

If you are working on a physical or digital bust (portrait): : Focus on the undertones