You definitely need to get cycling shorts and/or knickers and/or tights first, because you're going to need the padding. Beyond that, it varies. The coldest I've ridden in is upper 40s, and I wore wool tights over cycling knickers and a merino wool long-sleeved jersey under a fleece vest, a buff to keep my neck warm, and cycling gloves with full fingers.

I was plenty warm and as the day heated up into the 50s I shed the wool tights and fleece vest and buff.