The one thing worth knowing is that sheer only works when something underneath is doing a proper job. A flimsy nude cami that pretends to be invisible just reads as sad and beige under bright chiffon, and I say that as someone who has to force herself to say anything nice about beige at all. You want a lining or a layering piece with a bit of structure and the right colour weight, not a prayer and a vest top.
In the shop, hold the fabric up to the light before you do anything else, because that tells you more than the label does. Cheap sheer tends to be flat and a bit plasticky, it clings in the wrong places and goes see through in a patchy, unflattering way rather than an even, deliberate one. A better version has some drape to it, moves when you move, and the sheerness looks like a choice rather than an accident. Check the seams too, and whether there's any stretch at the cuff and neckline, because sheer fabric with no give will show every pull and pucker by lunchtime.
This is a lovely thing for the in between months, spring into early summer and then again in September, when you want colour and some bit of interest on top but it's not quite warm enough to go sleeveless and bare. Layered over a good camisole it does a long lunch, a wedding guest outfit, a Friday that started as work and ended somewhere nicer. On its own, properly lined, it's a brilliant going out top, the kind of thing that photographs with texture instead of just looking like a block of colour.
I had a delivery of ranunculus in once in the palest coral, almost see through at the edges where the petals thin out, and that's exactly the trick a good sheer top pulls off, colour that has light moving through it rather than just sitting on it. That's the print or colour to look for, something with enough depth that sheer doesn't flatten it into nothing.
For pairing, keep it simple underneath, a plain cami or a fitted vest in a colour that either matches or properly contrasts, and then let your trousers or skirt do the grounding, denim, tailored black, a good midi skirt, all take it fine. Don't overdress the rest of the outfit, the top's already giving you plenty.
Try it on and raise both arms properly in the changing room, because that's when a badly cut sheer top rides up and shows you something you didn't mean to show anyone.