While in the 30's a good skincare regimen consisted of cleansing, exfoliating and moisturizing, the 40's are a time to start thinking anti-aging products. Some of the best ingredients to look for are alpha hydroxy acids and retinoids, both which stimulate collagen production.
Also, your skin type might change. I noticed that my skin, which used to be normal/combo, began to go more toward the dry side. If this happens, switch to a creamy cleanser (instead of a gel or foam) and a heavier night cream. Just make sure to choose oil-free formulas if you're still experiencing breakouts, which can easily happen due to fluctuating hormones.