A tablecloth earns its place in a house where people actually eat at the table, kids included, wine included, the occasional candle wax drip included. If your dining table is mostly a landing spot for mail and a laptop charger, skip it, because a good cloth wants a reason to come out, not a reason to sit folded in a drawer for a year.
When you're looking at one in person, or pulling it out of the delivery bag, run your hand across it before anything else. Cheap cotton blends feel thin and a little papery, and you'll know within a season because they pill where elbows rest. A heavier linen or a tight cotton weave has some weight to it, it sits on the table rather than floating, and it makes a proper soft thud when you drop cutlery on it instead of that clattery bare wood sound. Check the hem too, a rolled or mitered hem lies flat, a cheap overlocked edge curls up at the corners within a few washes and never quite lies right again.
Linen softens the more you use it and wash it, which is the whole point of buying it in the first place. It goes from slightly stiff and formal out of the packaging to something with real drape and movement after ten or twelve washes, and it starts to feel almost like a worn shirt. Cotton holds its shape longer but doesn't soften the same way. Either way, wash warm not hot, skip the dryer if you can stand it because heat is what kills the weave over time, and treat stains the day they happen, not the day after a dinner party when everyone's gone home and you're too tired to deal with it.
Color is where people get nervous and I get opinionated. A plain white cloth is safe but it shows everything, every ring, every splash, and it photographs better than it lives. I'd rather see a deep color, a rust, an ochre, a dark green, something that hides a little life and still looks intentional with mismatched plates. What it clashes with is anything busy underneath it, a patterned rug and a patterned cloth fighting for attention makes a small dining area look chaotic rather than warm. And skip it entirely on a table you use for homework or crafts five nights a week, that's a wipeable surface job, not a textile one.
Give it a few years and it stops looking like a thing you bought and starts looking like a thing you own. The creases fall differently, the color mellows a shade or two from washing, and it drapes over the table edge the way it never quite did in month one. That's the version worth keeping.