I would say that in general backpacking tours are aimed at people in their 20's and early 30's. I've been on backpacking tours that had people of all ages, so there is no set in stone age you need to be.
Backpacking_Tours.html
One of the biggest challenges for a winter backpacking is clothing. Many times a person will go about dressing for cold weather in the wrong manner.
Winter_Backpacking.html
What about a backpacking Europe adventure? There are a lot of things you need to know when traveling from country to country overseas.
Backpacking_Europe.html