Serum - What do to with it?

[PonyPatter44]

Oh dear. I have serums (two from my beauty advent calendar, and one as a sample from Chanel), but I genuinely don't know when I should use them. Do I put serum on before my moisturiser, or just on its own?

Serum before moisturiser.

What are they? Some are better in the morning, some in the evening. If they have actives, then some shouldn't be used at the same time as other products.

If your skin isn't dry and your serum is a hydrating one, you might not need a moisturizer. Nadine Baggott uses just serum for example, but I couldn't.