Layers because it is often that we overdress rather than underdress, then drying sweat makes ya cold.

I do:

polyester or other synthetic base layer (either a jersey or a tight fitting underarmor shirt)

light alpaca wool or other wool sweater

high vis windbreaker (that has no insulation.) It breathes, but keeps the wind out.

If it's raining, gym warmup pants over my capris or shorts.

Wool socks.

garden gloves over a liner (sometimes.) You can get those rubber dipped garden gloves at the hardware store - they are nice because the rubber grips, is tough, and insulates, but the fabric side breathes.

Alpaca hat/beanie or a synthetic balacava or a synthetic (coolmax) buff under the helmet.

That's it!

It starts out chilly, but after five minutes I am warmed up. Best, I am not overdressed, which I think is worse than being underdressed. I hate being hot on the bike.