Ornaments used to mean one box of mismatched glass balls passed down until half of them were bald patches of silver, and honestly that had its own charm. The last few years have tipped into something else, whole trees done in one color story, finishes coordinated like a paint chart, and I think it's mostly for the better. A tree that looks thought about, even loosely, reads as warmer than a tree that just happened.
What separates the good ones from the sad ones is mostly in the hand, not the box photo. Pick one up. Glass ornaments should feel like actual glass, thin walled and a little heavy for their size, with a cap that's crimped on tight, not glued, because glue goes first and you lose the ornament off the hook by January 2nd. Painted finishes should have some texture or sheen variation up close, not one flat coat that looks like it came off a printer. Fabric and felt ones live or die on the stitching, tight and even, no stray thread trying to escape. Cheap ornaments are shiny in a way that reads plastic from across the room, and once you've noticed it you can't stop noticing it, it's like bad highlights, you see the line forever. On the tree, ornaments sit well against a strand of warm white lights and not much else fighting for attention, they crowd out a tree that already has tinsel, garland, and a topper all competing, pick two of the three and let the ornaments be the main character. If you're starting from nothing, don't buy forty of one thing, buy a smaller set in one finish family, say a matte and a shine in the same color, plus a handful of something textured like felt or wood for contrast, that mix fills a six foot tree without looking like you bought a kit. A deep emerald and gold mix does something a plain red and green can't, it reads rich instead of expected, my mother's tree is red and green every single year and it's fine, it's just not a conversation. These suit any home that actually puts up a real tree, apartment or house, and they suit the whole stretch from first snow through New Year, not just the big day, since nobody takes the tree down on December 26th no matter what they tell you in October.
If I were starting a box from zero, I'd go with a warm gold finish first, it glows under any light, clashes with nothing, and makes even a sad little tabletop tree look like you meant it.