Ditto to Una's last sentence! I warm up quickly. Today it was in the low 40s when I started out, and I had on new running pants:
http://shop.lululemon.com/prod.....omen-pants
A new shirt:
http://shop.lululemon.com/prod.....women-tops
And a very lightweight jacket. After the first 2.5 mile loop, I ditched the jacket in my car, and by the time I finished my second loop, the temp was nearing 50 and I was definitely sweating.
So my strategy is generally light layers, but no more than three. I have an Under Armour fleece that is an excellent outer layer when it's cold, and a windbreaker for when it's windy or rainy, but I could use a new one of those.
I also wear lightweight gloves, but they usually come off after the first mile or so. If its really cold (like when I ran in NYC last Feb in 17 degree weather), I'll put wind proof mittens over the gloves. I also use one of those Buffs around my neck (or sometimes my head to keep my ears warm), but again, it usually comes off and gets wrapped around my arm or something after a couple of miles unless it's really cold! And I almost always wear a cap to keep my hair out of my face and the sun off my face as well.
I'd rather run in the cold than the heat any day!