Going by complimentary color theory, green or bluish-purple attire works best with redheads. Green if they have ginger, orange colored hair or bluish-purple if they have dark red, crimson hair or medium brown hair.
Blue works best for blondes (yellow hair).
Red works best for black hair (as well as red lipstick if you wanna add makeup to it).
Orange clothing pretty much never looks good on anyone. Pretty much, only if they had indigo or turquoise colored hair could they make orange look nice on them. Otherwise, don't ever wear orange clothing.
I, being a natural redhead myself, completely agree that the (light) blue swimsuit will be best. It will contrast your friend's hair while complimenting the skin. Blue is really the only color you can go light on for a redhead, some greens work, but blue works best. An alternative to the blue one would be the dark green one in the last/bottom pic. Green usually works well on a redhead, especially a dark green, but if all else fails, go black. The black will contrast the hair and skin and give a dark/goth vibe. The other colors here will only clash and look horrible on your sexy friend, who I wouldn't mind meeting if she's single ;)
I like the black one. I don't like the draped ruffle on the last one and I don't like asymmetrical garments. If you can get the third one in a shade of green that will contrast your red hair.
#4. The off the shoulder, single strap look is sexy. And I think that color would off set red hair really well. Is her hair dark red, medium red, or ginger?
Do not get a red bathing suit for a redhead, it clashes... Go for something that sets her redhead off, like the green one at the bottom or the blue one that you like. either would look good on her.
