As a kid, and with my own child, we always shopped for (or made) 2 new ornaments a year, with dates (or we added the date on the bottom, etc). We did 2 so that when dd moves out (just as when I did), one of the ornaments from each year goes with me, the other stayed at home with Moms giant tree. That way we have a starter set for our own Holiday tree!
Eventually I got the other ornament set as well when my M. died 4 years ago, but she had 18-20 ornaments carefully wrapped in tissue, in a fancy little treasure looking box she had bought at some point and fancied up (she was crafty but had bought them when we were adults so they were all the same, had each of us 4 kids names on them..and even had some she had done with the grandkids..so a few smaller boxes).
I have the set for my daughter too (she is 17) so she will have her "starter set" whenever the time comes that she sets out on her own and makes that first tree.
I remember my first tree with my now-hubby. We bought a huge fat real tree (I always had a real tree up till then, and his memory was a real tree on his "happy" years), and had to go buy lights and a star for the top and ornaments. He loved how almost reverent I was openeing my little shoebox (thats what it was at the time) of ornaments. Many of my little years were school made ones, or the ceramic homemade ones we did with my Godmother who lived next door...the pipecleaner and button elves with the teeniest bells on their caps, etc. He never had consistent tradition or events with his crazy fighting divorced parents (mine were divorced too but my M. loved Christmas and made it very special , even poor as we were!), so this was a big deal to him to see!
Good luck finding what works for your family!!