Always wear sunscreen daily! Pigmentation will worsen or keep reoccurring without proper sun protection.
Brighten and fade sun spots or post inflammatory acne pigmentation by using an alpha hydroxy acid exfoliating serum like glycolic or lactic acid 2-3 times per week. This can be used interchangeably with a retinol to stimulate cellular regeneration for for a smoother, more even skin tone.
Use a concentrated Vitamin C serum, or antioxidant rich oil (like rosehip or seabuckthorn oil) to help brighten and even out skin tone.