To cover a scar with makeup, try using a color correcting fluid in green, a heavy duty concealer and translucent powder. This method helps cover the scar and negates any redness.
For scars that are irritated or red, start by applying a green color correcting fluid, like Physicians Formula Conceal Rx Physicians Strength Concealer in Soft Green. Then use a heavy concealer, like Benefit Cosmetics Boi-ing Concealer, to make the scar disappear. Use a finger to gently tap the concealer onto the scar. When the scar is sufficiently covered, finish the look with a touch of translucent powder. Maybelline New York Mineral Powder Finishing Veil Translucent Loose Powder is an affordable choice.