Decor is the stuff that doesn't do anything useful at all, and that's exactly the point of it. No function, no job to perform, it just sits on a shelf or a mantel or a console table and makes the room look like someone with actual taste lives there instead of someone who just unpacked boxes and gave up. It's the difference between a room that's finished and a room that's furnished.
The easiest colors and finishes to live with are the ones that don't compete with anything else in the room, so think warm neutrals, aged brass, raw wood, matte ceramics in cream or clay or a deep muted green, the kind of thing that looks like it's always been there even on day one. Bright colored glass and anything glossy white photographs well but gets tired fast and starts to look like it belongs in a hotel lobby rather than your living room. If you're starting with nothing, don't buy five small things, buy one or two pieces with actual presence, a vase with some height to it, a bowl big enough to hold something, a piece of textured pottery that can sit alone on a shelf and still look intentional. Small scattered trinkets just read as clutter until you have enough of them to tell a story, and most people don't have the patience or the shelf space for that collection to build up naturally.
In a shop or the day it's delivered, check the base and the weight of the piece before anything else, because a vase or bowl that feels light and hollow will tip over the first time a cat or a toddler walks past it, and you will find out the hard way, probably at 7am on a weekday. Check the glaze for pooling or pinholes if it's ceramic, check that wood pieces are actually sealed and not just stained, and if it's got any kind of metal finish, rub your thumb across it in the shop, cheap plating rubs off within months and leaves a dull patch exactly where you touch it most. Over time, good decor should age the way a cast iron pan does, slightly better, with character building up rather than wearing down. Ceramics and stone just need a damp cloth now and then, wood wants an occasional wipe of oil, and brass will darken a little unless you polish it, which honestly looks better once it does.
If I were starting from zero, I'd pick something in warm cream ceramic or aged brass over anything trendy or bright, because five years from now it'll still look like it belongs.