Being skinny with a slow heart rate, I stay cold at anything below 70. Before spending a lot, try experimenting first. Find a large thrift store or salvation army and buy a dozen various items that look like they might work at anything between 20 and 70 degrees. And a small backpack. For twenty bucks you can field test out a lot of combinations. Basically you are going to find out what does NOT work and then spend good money for good gear that fits what you've found out you need.