How can I mail my goods from US to Canada without duty?

[atacama]

I plan to do a landing at a US-Canada cross border. Then my friends will mail my goods from US to me. There is a duty when the goods are more than $20. I understood that when I do the landing, I can provide a goods to follow list. Then do I need to print out the GTF list and paste it on the packages? I just don't understand how this process works.. Can someone please share some experience?