Ive reached the point (or prices have) where I don’t think this budget is that easy.
So I would start by spreading out literally every rag I owned, very much including any accessories, and look at it with an outsiders eye. What do I own that I enjoy wearing, feel good in, like everything about (colour, fabric, shape, fit now)? I’d put everything else in a temporary bin bag and then consider the remaining bits as the basis of the wardrobe. I’d make a list of things I think would fill the gaps to make outfits, and then I’d start looking. I agree re Vinted, though I prefer a high end charity shop or dress agency so I can actually feel fabrics.
As a recovering scruffbag with no waist I would say it is much easier to look pulled together with dresses or jumpsuits than separates. But in the winter you need coats to keep that look going, and coats the right length.
I’m not a fashion person at all but pace Meryl Streep, there are shapes and colours that the fashion industry ensure just look wrong, so it is worth updating yourself. I do look to see what shapes and fabrics are out there. Broderie anglais is everywhere I go this summer and I like it, and I’ve bought a dress in it.
Without wanting to sound like a twat, decent shoes and imo socks make a huge difference. I have horrible pronated buniony feet, and I can’t look or feel anything but awful in the wrong shoes. I would probably have to start there tbh as I would need to spend a few hundred on footwear.
Do you have pierced ears? ( I don’t.) Can you get some upscale earrings for a birthday or even within the budget? They do a lot of heavy lifting.