Unless it is really cold and windy (like 0F and calm or 10F and really windy), I just wear a fleece earband. I tend to sweat too much (which in winter is your enemy) if I wear anything more. The band keeps my forehead and ears warm which are the areas that get cold on my head before anything else. FWIW, I have long hair, which acts as a windbreak under the helmet (just a standard "summer" helmet, btw).

When it starts heading into single digits and below, I may throw on my ski helmet (less venting), add a silkweight balaclava, or a neck gaiter. It is all a balance of temperature, wind, and heat production. I tend towards high in the last department, so my system may not work for you. But, if you think of the balance between wind blocking and insulation (they are different), then you should be able to arrive at a good solution.