You can buy a lot of sweater, t-shirt, jacket, shirt and glamourize your clothes, ennoble it with accessories.
I recommend a nice brooch on a jacket, a jewel often forgotten. The brooch can be made of metal, rhinestones, bakelite, retro, vintage, feather, silk, leather, in the form of a flower.
You mustn't choose it too small. And, if you're afraid that it will look too small, you accumulate them, you put two or three on, making sure that they harmonize in terms of colors, shapes.
If you want to wear a plain dress (black or other), observe the construction of the dress: where are the seams and topstitching ?
Respect the symmetry and do not hesitate to place the brooch in the centre if the topstitching seems to impose it.
On a sweater, to prevent the weight of the brooch from pulling and distorting it, put on a necklace or several, or cascades of pearls, Chanel style - pearls, always flattering to the complexion; bright colours too, as well as gold or silver. Each skin tone has its own metal "sound". Just avoid the little chain with a medal or a small pendant, it's not creative at all.
If you like a necklace with bare branches, put it on a blouse, the collar allows you to hide the bare branches. If you like earrings, and you're lucky enough to have a long neck, big geometrical earrings or big decorations, it's very design, it personalizes a style. And put only that on.
To give style and elegance to the sweater, a silk scarf in bright and vivid colors changes everything! Of course, you have to know how to tie it: not on the front, grandmother style, but on the side, and if necessary, fixed by a pin or a pin hidden underneath. And don't always wear the same one!
Finally, a good way to accessorize a jacket - or a coat - is... brooches, the best accessories in the world that will make you unique. This way, you impose a personal taste on a standard outfit. And that's exactly what you want to do!