White goes against a lot of colours I'd normally reach for first, and that's exactly why I keep one on the counter at home, next to the key dish, so I actually put it on instead of leaving it in a drawer with the hair bobbles. The one thing worth knowing before you buy: white reads differently depending on what's underneath it, so a cool white bracelet against warm skin can look chalky, and a creamier white against cool skin can look a bit grubby by lunchtime. Hold it against the inside of your wrist in the shop, not under the shop lighting at the till, actual daylight if you can get near a window.
If you've none at all, start with something simple and a bit solid, a bangle or a chunkier beaded stretch bracelet rather than anything delicate and fiddly, because a thin white bracelet on its own can look like it escaped a wedding favour. Something with a bit of weight to it holds its own against a plain jumper or a denim shirt, and it photographs as a proper piece of jewellery rather than a party bag extra. I bought a thin wire one years ago thinking it would be dainty and lovely, and it just looked like I'd lost the other half of something.
In the shop, check the finish close up, because white shows every flaw. Run a finger over it, if it's got a seam or a rough join it'll catch on jumper sleeves within a week. Check the clasp too, white enamel especially can chip at the hinge, and once it chips it shows up like a missing tooth. If it's a bead bracelet, give the elastic a gentle stretch, cheap elastic perishes fast and you'll be picking beads off the kitchen floor by fifth wear, I've been there, down on my knees looking for a bead under the fridge like it owed me money.
Where it earns its keep is against colour, not neutrals, oddly. I've got buckets of tulips in every shade going past the counter this week and the ones that stop me are the bright orange next to plain white paper, so a white bracelet against a coral or cobalt top does the same job, it gives the eye somewhere clean to land. It's lovely with denim and a stripe top too, properly ordinary, nothing clever about it, but it lifts the whole arm. Against black it goes a bit stark and corporate, which some mornings is exactly what you want. Try it with gold rings rather than silver if your skin runs warm, it softens the white instead of fighting it.
If it's loose enough to spin fully round your wrist with one finger, it's too big, go down a size.