I hold on to everything unless it's damaged. I have a friend whose son (age 12) recently started collecting and I went through a bunch of my duplicates and gave him around 2,500-3,000 stamps. Most were probably worthless but you would have thought, from his reaction, that I had given him a pot of gold. As an aside, I put together a used set of 2012 Scott Catalogs on
ebay recently and gave it to him for Christmas. I had very little invested in them but his dad told me that he spends hours at a time identifying and looking up the stamps I gave him. The moral of this story is to not throw anything out. Even though the number of new collectors is not what it used to be, there
are some out there and would treasure what you may consider as junk. Remember, they are the future of philately.