Whiteheads, visible pores, redness, and marks can result from factors such as clogged pores, excess oil, skin sensitivity, irritation from skincare products, and other individual skin conditions. Since you are already using multiple products, including a salicylic acid serum, and still experiencing these concerns, adding more products without understanding the cause may worsen irritation. Avoid squeezing or pinching whiteheads, as this can increase redness and leave marks. The best product or treatment depends on your skin type and the severity of your concerns, so it is recommended to consult a dermatologist for proper skin evaluation and a personalised skincare routine. In the meantime, continue a gentle routine with mild cleansing, suitable moisturisation, sunscreen use, and avoid overusing active ingredients.