Hold a quarter zip up and check two things before anything else: how the collar sits when it's zipped right up, and how much room there is through the shoulder. If the collar stands up stiff and tall rather than folding softly, it'll dig in under a coat all day. If the shoulder seam sits properly at the edge of your shoulder rather than halfway down your arm, it'll layer well. Get those two right and the rest of the outfit sorts itself out fairly easily.
The thing to avoid is bulk on bulk. A thick quarter zip under a padded coat just makes you look like you've borrowed someone else's body, and a chunky knit version under a blazer will strain the buttons and pull at the back. Keep the layer under or over it slim, a cotton tee underneath, a lighter jacket on top, and let the zip be the texture that stands out rather than competing with another heavy fabric. Same goes for necklines, skip the fiddly scarf or statement necklace, since the zip and collar are already doing that job. For the time of year, this is really an in between piece, too warm to be useless in fifty degrees under a coat, not warm enough on its own once it's properly cold, which makes it brilliant for the stretch either side of winter when you're constantly taking a layer on and off. It also does well for anything active but not sweaty, a morning dog walk, the school run, sitting outside somewhere with a coffee. For colours, you want ones that sit happily against jeans and trousers without you thinking about it: a soft grey, navy, a muted olive, or a proper oatmeal all go the distance because you can wear them under practically anything without a clash of tone. Avoid very bright or busy colours unless you genuinely plan to make the zip the whole outfit, because they're harder to layer and tend to get worn alone, which means they get worn less.
Where it falls short is anywhere that wants structure or a finished look. A quarter zip under a smart coat for an evening out just reads as underdressed, no matter how nice the fabric is, because the shape is sporty by design, round and soft rather than tailored. If you're after something for an occasion where you want to look put together rather than comfortable, this isn't it, and no amount of good accessories will fully fix that. It's also worth being honest that a boxy fit on a smaller frame can swamp you, so if that's you, look for one with a bit of shaping at the waist rather than a straight drop.
Start with a grey one. It goes under or over almost anything you already own, and it won't fight with a single coat in your hallway.
