Layering only needs one rule, and it is not the one most routines are built on. The order that matters is thinnest first, thickest last.
Water before oil
A watery product applied over a rich cream mostly sits on top of it. The same product applied first goes where it is meant to, and the cream over it slows what evaporates. So: anything liquid, then anything lotion-like, then anything that feels like a balm.
If two products feel about the same thickness, the order between them makes almost no difference. It is worth less worry than it usually gets.
Fewer layers, especially for drier skin
Every additional layer is another ingredient list, another chance of something stinging, and another step to abandon on a tired evening. Skin that is already thinner and drier gains less from a long routine than from a short one done properly.
If a step does not have a job you can name, it does not need to be in the routine.
A rich cream that carries its actives inside it removes the question entirely, because there is nothing left to sequence.
Two things worth getting right
Sunscreen goes last in the morning, over everything, and on its own. Mixing it into a moisturiser to save a step thins it out, and it is the one product where how much you apply is the whole point.
And you do not need to wait between steps. Waiting for a layer to dry only helps if the next one will not spread evenly over it, which for a serum and a cream is almost never the case.
This article is general information, not medical advice. Speak with a qualified healthcare professional about your own skin, and do not use retinol during pregnancy or nursing without their guidance.
