The moment is always the same one, plugging in the lights for the first time and standing back to see what the tree actually looks like with everything on it, not just the bare branches and a string of bulbs. That first look either makes the whole room or tells you you've got some buying to do. I've had both nights, and the good one is better.
If you're starting from nothing, don't buy a box of forty matching ornaments and call it done, that's how you end up with a tree that looks like it belongs in a hotel lobby. Pick one material to anchor things, glass or wood, and build out slowly from there with a few pieces a year. That's genuinely more satisfying anyway, a tree that's half family hand me downs and half stuff you picked out on purpose looks lived in, which is the whole point. Where it goes wrong is mixing finishes that fight each other, a bunch of shiny mirrored glass next to matte painted wood, next to glittery felt, all competing for the same six inches of branch. Pick a lane. Warm metallics with wood and fabric reads calm. All glass and crystal reads formal. Doing both at once just reads like you cleaned out two different relatives' attics in the same afternoon.
The difference between an ornament that lasts and one that's garbage by January shows up fast. Glass ones should have a proper metal cap, crimped on, not just glued, because the glued ones pop off the first time a cat looks at them funny. Wood ornaments should feel like actual wood, some weight to them, not the light balsa stuff that chips if it taps the wall. Painted finishes matter too, a good one is sealed and smooth, a cheap one leaves paint dust on your fingers after one Christmas. I learned that one the hard way with a set of painted birds that basically molted all over the tree skirt by New Year's. Fabric and felt ornaments should have real stitching at the seams, not hot glue holding the whole shape together, because hot glue gives up by year three.
These sit easiest in a room that already has some warmth to it, a wood floor, a wool rug, a mantel with actual stuff on it rather than bare brick. A plain green tree against a plain white wall needs the ornaments to do all the talking, so that's exactly where the good ones versus the cheap ones shows up most.
Next to the tree itself, I'd put a simple tree skirt in a plain fabric, nothing patterned competing for attention down at the bottom.