Vitamin C serum can help, as can any number of skin lightening potions. Nothing really speeds up the fading process very much though. The best thing is to prevent new breakouts. Have you tried a daily regimen of benzoyl peroxide? BP works well to prevent acne IF you apply all over the area before you breakout, not after. BP is cheap, but it will bleach your sheets and towels, so it's best if you use white sheets and wash off thoroughly before using a towel.