Mixing tretinoin cream with moisturizer is a common practice known as buffering. Buffering can help to reduce the irritability of tretinoin, making it more tolerable for those with sensitive skin. This is particularly helpful when first starting tretinoin, as it can help your skin adjust to the medication. While buffering can potentially decrease the potency of tretinoin slightly, it's generally considered a worthwhile trade-off for those who otherwise wouldn't be able to tolerate the medication. Ultimately, it's better to use tretinoin consistently in a buffered form than not at all due to irritation. However, if you want to maximize the anti-aging benefits and your skin has adjusted to tretinoin, you could consider applying it directly to your skin, waiting for it to absorb (about 20-30 minutes), and then applying your moisturizer. This might provide a bit more potency without significantly increasing irritation. Always consult with a healthcare provider or dermatologist before changing your skincare routine. They can provide personalized advice based on a thorough understanding of your skin's needs and sensitivities.