The question I get asked most about going out tops is whether you can find one with proper sleeves and a neckline that sits high enough to not need fixing all night, without it looking like you've compromised on the whole point of the top. You can, and it's usually the ones with a bit of structure in the fabric rather than the floatiest option on the rail.
Colour wise, I always go back to a deep jewel tone or a true black satin finish over anything metallic, because metallics crease the second you sit down and then you're standing against a wall all evening trying to look casual about it. A rich emerald or a plum does the same job as sequins without the maintenance, and it photographs better under bad pub lighting too, which nobody tells you until you've already bought the gold one. For pairing, a going out top earns its evening if it works with the trousers you already own rather than a whole new outfit built around it, so I look for ones that sit well tucked into a high waisted trouser or a straight leg jean, something with enough weight in the fabric that it doesn't ride up when you lift your arms, which I always test right there in the changing room, arms straight up over my head, because a top that gathers round your ribs at that point will do it again on a crowded dance floor and there's no fixing it discreetly. A long sleeve underneath in a matching shade turns a sheer or low cut one into something I'd actually wear, and it barely adds bulk if the sleeve is fitted rather than flowing. As for how they age, the good ones soften slightly after a few washes and keep their shape, while the cheaper polyester versions go slightly see through round the shoulders within a couple of months, so hold the fabric up to the light in the shop, properly up, not just a glance, and if you can see the shadow of your hand through it in a normal shop light, imagine what a flash photo does to it. Hand wash or a cold cycle in a bag keeps the drape, and never tumble dry anything with a satin finish unless you want it to come out looking like it's been in a scuffle.
The ones worth keeping are the ones that still look sharp after a dozen wears and a few hand washes, not just under the one set of lights they were bought for.