Hiking websites recommend wearing layers, because these make adjusting between warm and cold weather or uphill and downhill walking simple. One thick garment would only work for cold, but taking it off when it gets too hot may leave only too thin clothing.
The same principle of layers applies for everyday clothes. My office is 12 degrees in winter mornings, so I wear two pairs of pants, sometimes two vests and a fleece. Instead of one thick pair of pants that would only suit cold temperatures, thin pants can be worn singly in warm weather and doubled up in cold.
For cycling in the cold, shorts can be worn under long athletic slacks. This principle should also work for hats – two thin fleece ski caps instead of one thick, but I have not tested it. Similarly, two pairs of socks. Although, just like with thick socks, if doubled socks make the shoes fit too tightly, then the reduced circulation increases the cold feeling.
Toe warmer making instructions on the internet suggest using the cut-off front parts of old socks. A more multifunctional option is to roll back existing socks halfway, so both the toe and the ankle part of the sock cover the toes, as in the following image.
Cut socks only work as toe warmers, but rolled-back socks can be used year round.