A basic tween skincare routine could contain a cleanser, moisturizer, and sunscreen. A good sunscreen is a must with SPF 30 or above, and for extended time outdoors, preferably SPF 50 or above. If you have acne or acne prone skin, you could use small concentrations of salicylic acid and benzoyl peroxide as either a spot treatment or incorporated into your cleanser.
Establish a simple routine that focuses on all the necessities needed, and don't over-do the amount of ingredients or your skin may become irritated.
Ceramides, hyaluronic acid, squalene, etc. are ingredients that are good for your skin barrier and can also help reduce acne and appearance of redness on the skin.
Physical exfoliants - Products like scrubs that contain beads or particles which can cause redness on the skin.
Harsh exfoliating acids - Products that contain AHA or/and BHA which can cause irritation
Retinoids/Retinols - Harsh and unnecessary for tween skin.
Succinic Acid - This is well known for fighting acne, and it is gentle and less likely to cause irritation or dryness.