The pieces worth having are the ones you reach for without thinking, not the ones you buy because they photographed well on someone else. I say this because I've bought plenty of the second kind over the years, worn them twice, then watched them sit at the back of a drawer looking faintly accusing. The ones that actually get used are usually plainer than you'd expect and a bit less exciting on the hanger.
If you're starting from nothing, go for the simplest version of whatever you're drawn to, a plain jumper rather than one with a slogan, a straight trouser rather than a cropped one with three buttons that only do up if you breathe in. Simple pieces are the ones that sit happily next to the jeans you already own, the work trousers you've had for three years, the skirt you bought for one wedding and then kept because it turned out to be useful. Build around what's already in the cupboard rather than buying something that only works with clothes you haven't bought yet.
The difference between a cheap one and a good one shows up slowly, which is exactly why people get caught out. A cheap jumper looks fine for the first few wears, then the cuffs go baggy and the whole thing starts to pill under the arms by week six. A better one, same shape, same colour even, keeps its line because the yarn's been spun properly rather than just dyed to look nice in a photo. Wash things the way the label actually says rather than the way you assume, and turn knitwear inside out before it goes anywhere near a machine. A good piece looked after properly will see you through two winters without losing its shape. A cheap one will have done its job by Christmas, and not the second one.
Stick to colours that don't ask anything of you. Navy, a soft grey, a brown that isn't trying to be a statement, these go with almost everything you already own and never look dated next to it. Bright colours and bold patterns are lovely in small doses but they date a wardrobe photograph far faster than a plain one ever will, which is a kinder way of saying they're harder to keep wearing past one season.
Add one of these to something you already wear on repeat, and it stops looking like the same old outfit and starts looking like one you chose on purpose.