When the team changed their kit I had to think about what I wanted to buy. This is what I got, in this order:

1. Jacket (warm, not just wind resistant but also insulating). This one the sleeves zip off.
2. Wind vest
3. Long sleeve jersey (after getting 3 or 4 sets bib shorts and jerseys, plus arm warmers which I almost never use, plus lycra shoe covers)

I have shoe covers (lycra, knit sock-like covers, and finally insulated booties), long finger gloves (summer and winter - I always wear them, even in summer), and head covers (thin or thick lycra type).

Finally the key for me are 3/4 shorts aka knickers. I have them in the "roubaix" fabric (brushed on the inside so it's a bit more fuzzy, more insulating, wicks moisture away). I have a bunch of those as I wear them from 35-55 deg F, and I rarely ride outside below 35 deg F. Knickers are especially good when it's raining out because they don't get as heavy as tights, and wet they're both about as effective in keeping me warm. Shorts in the cold rain exposes the knee to wind and so it's just a bit too cold.

I find knee warmers leave the (ahem) upper parts cold. A teammate bought some winter weight bib shorts but I haven't heard reports from him. The theory is to combine those with knee warmers to get a modular version of the knickers I have. I can't get team shorts in winter weight so for now I'll stick with the knickers since I have 4-5 pair of current ones.

Keep your torso, hands and feet warm. At 55 deg I'm in shorts but with booties, long sleeve top, wind vest, long gloves, head cover. I prefer some coolness on my arms/legs and a very warm torso.