To achieve even application with crayon hair color, start by sectioning your hair into manageable parts and applying the color evenly from roots to ends. Use a comb or brush to distribute the color smoothly and blend any harsh lines for a seamless finish. Avoid applying too much pressure; gentle strokes ensure better color saturation without damaging the hair. Additionally, setting the color with heat or a hairdryer can help enhance its longevity and vibrancy.