A couple more tips on equipment. I use a very thin hat designed for cross country skiing that fits easily under my helmet and keeps my head warm in the coldest weather. Also, if you get some glasses with interchangeable lenses then you can use the same ones year-round if you get some clear lenses (good for night riding).

A lot of cycling magazines discuss this kind of thing, normally in the fall or early winter. You can get an international subscription to the US-based Bicycling magazine for just US$40, and I also like the Cycling Plus magazine from the UK, the international subscription is a bit expensive for that so I just pick up a copy whenever I'm there or ask visitors to bring one with them from there.