longjohn baselayer under your shorts. I like polyester ones. Or two.
Layer merino/polyester baselayers. I have some that are skin tight and some that are looser, like t-shirts. Varying thicknesses. Long and short sleeve. They layer well. I'll wear 3 baselayers before I add a mid-layer.
Outer layer is very thin polyester red thing with hood. purely for stopping wind. I strongly advise avoiding waterproof garments on a bicycle, unless it's raining (heavily), because you'll just drown in sweat. If it's not enough to cut windchill, i layer another similiar thing (the one between the down & rain shell).
If it's REALLY cold I add down.
If it's raining/snowing, rain jacket. Legs just get wet.
gloves & stretchy neck thing too when it's cold enough.