My first beaded bracelet was a stretchy cord strung with painted wooden beads, bought off a market stall for about three pounds when I was far too young to know better. It snapped on a bus within a fortnight, sent beads rolling under every seat, and taught me that with these the cord matters a lot more than the beads ever will.
Getting the fit right is almost entirely about the elastic, not the beads themselves. It needs to sit snug enough that it doesn't slide down over your hand when your arm drops, but loose enough to pull over your knuckles without a fight, which sounds obvious until you're standing in a shop doorway wrestling one on like it owes you money. Measure your wrist loosely with a tape or a bit of string before you buy, and if a bracelet feels tight going on, it will only get tighter once the elastic warms up and stretches with wear, so it's better to size slightly generous than snug. Watch for beads that are large or sharp edged sitting right on the wrist bone, that's the spot that rubs and bruises on a long day, and watch the knot or crimp at the join, because that's always the first thing to give. If you've got none of these at all, start with a single row in plain wood, stone or matte glass beads in a neutral colour, rather than anything bright or multi strand. One simple row goes with a plain jumper, a denim shirt, a white tee and jeans, pretty much anything you already own, where a loud multi coloured stack needs you to think about what else you're wearing before you put it on.
Once you've got that first one, the more useful habit is building a small collection of singles rather than buying one chunky multi strand piece, because singles let you add or take away depending on the day, and they're far easier to replace individually when one inevitably perishes. Elastic does perish, even the good stuff, so give each one a gentle stretch test every few months and retire anything that feels slack or looks whitened along the cord. These earn their place most in warmer months and casual settings, holidays, weekends, days when your wrist is bare anyway and a watch feels like too much effort, and they layer nicely with a slim bangle or a simple chain if you want more going on without it looking like you tried too hard. They suit someone who wants a bit of colour or texture on the wrist without committing to anything precious or expensive.