Layering helps! Some things that I'm combining a lot at the moment are:
Bottoms -
Indigo skinny jeans (the Gok for Sainsbury's ones are surprisingly good, and only £28);
Black skinny jeans (the M&S jeggings are excellent, cost me £22);
Black leather skirt, a-line and knee length (ebay is great for these - mine was £5 nearly 10 years ago and still looks perfect).
Tops-
A few vest tops in nice, flattering colours which don't clash with each other (Primark does lovely ones for £2);
Black cowl neck jersey top with long sleeves (black or charcoal, to taste - I have some lovely ones from H&M, bought last year for £12 each);
Black waterfall jacket in jersey (Wallis, £32 and worth every penny IMO);
Oversized chunky knitted jumper (I have two from Wallis which are very slightly sparkly and let the colour of your top show through the holes, they're lovely).
Shoes -
Nice black ankle boots.
Accesories -
Nice black bag;
Statement necklaces that go well with the colours of your vest tops;
Scarves that go well with the colours of your vest tops;
Thick black opaque tights.
As you can probably tell, I'm still getting over my adolescent goth phase so you might want to avoid some of the black. However, the above combine to make lots of different, practical but smart outfits and didn't actually cost very much money. A lot of it will also get used in spring and summer so it is quite cost effective, especially if you use ebay.